update git mirror

update-mirror.sh

#!/bin/bash                                                                                                                                                                                                         
set -e                                                                                                                                                                                                              
set -x                                                                                                                                                                                                              
                                                                                                                                                                                                                    
upstream_repo=${upstream_repo:-CENSORED}                                                                                                                                            
upstream_ref=${upstream_ref:-refs/heads/master}                                                                                                                                                                     
                                                                                                                                                                                                                    
target_repo=${target_repo:-CENSORED}                                                                                                                                                                 
target_master_branch=${target_master_branch:-refs/heads/master}                                                                                                                                                     
target_upstream_branch=${target_upstream_branch:-refs/heads/upstream}                                                                                                                                               
                                                                                                                                                                                                                    
git checkout --detach                                                                                                                                                                                               
                                                                                                                                                                                                                    
if git ls-remote --exit-code "$target_repo" "$target_upstream_branch" >/dev/null 2>/dev/null; then                                                                                                                  
  git fetch --no-tags "$target_repo" "$target_upstream_branch"                                                                                                                                                      
  commit=$(git rev-parse -q --verify FETCH_HEAD)                                                                                                                                                                    
else                                                                                                                                                                                                                
  commit=                                                                                                                                                                                                           
fi                                                                                                                                                                                                                  
git fetch --no-tags "$upstream_repo" +"$upstream_ref:$target_upstream_branch"                                                                                                                                       
if [ "$commit" ]; then                                                                                                                                                                                              
  commit2=$(git rev-parse -q --verify FETCH_HEAD)                                                                                                                                                                   
  if [ "$commit2" = "$commit" ]; then                                                                                                                                                                               
    exit 0                                                                                                                                                                                                          
  fi                                                                                                                                                                                                                
else                                                                                                                                                                                                                
  commit="$target_upstream_branch"                                                                                                                                                                                  
fi                                                                                                                                                                                                                  
                                                                                                                                                                                                                    
if git ls-remote --exit-code "$target_repo" "$target_master_branch" >/dev/null 2>/dev/null; then                                                                                                                    
  git fetch --no-tags "$target_repo" +"$target_master_branch:$target_master_branch"                                                                                                                                 
else                                                                                                                                                                                                                
  git branch -f "$target_master_branch" "$target_upstream_branch"                                                                                                                                                   
fi                                                                                                                                                                                                                  
                                                                                                                                                                                                                    
branch=$(git rev-parse -q --verify --symbolic-full-name --abbrev-ref "$target_master_branch")                                                                                                                       
git rebase --onto "$target_upstream_branch" "$commit" "$branch"                                                                                                                                                     
IFS= status=$(git status --porcelain)                                                                                                                                                                               
if grep -q -e ^.U -e ^U. <<< "$status"; then                                                                                                                                                                        
  exit 1                                                                                                                                                                                                            
fi                                                                                                                                                                                                                  
                                                                                                                                                                                                                    
tag1=master-$(date +%Y%m%d-%H%M%S)                                                                                                                                                                                  
tag2=master-latest                                                                                                                                                                                                  
git tag -f -a -m "upstream rebase" "$tag1" "$target_master_branch"                                                                                                                                                  
git tag -f "$tag2" "$tag1"                                                                                                                                                                                          
                                                                                                                                                                                                                    
git push -v -f "$target_repo" "$target_upstream_branch" "$target_master_branch" tag "$tag1" tag "$tag2