Example of setting up a Jenkins plugin backport branch

backport.sh

BASE=1.19 # or whatever; last release compatible with targeted core or other deps
BASETAG=mystuff-${BASE} # or as per http://maven.apache.org/maven-release/maven-release-plugin/prepare-mojo.html#tagNameFormat
FIX=abcd1234 # whatever the backportable fix was, in master or somewhere newer than $BASE
git checkout -b ${BASE}.x $(git log  --reverse --ancestry-path --pretty=%H ${BASETAG}..master | head -1)
# or for JEP-305 (“Incrementals”) use: mvn versions:set-property -Dproperty=revision -DnewVersion=${BASE}.1
mvn versions:set -DnewVersion=${BASE}.1-SNAPSHOT -DgenerateBackupPoms=false
git commit -a -m "Prepare for ${BASE}.1"
git push -u origin ${BASE}.x
git cherry-pick -x -m1 $FIX
mvn -B release:{prepare,perform}

# For JEP-229 (“CD”):
BASE=99 # numeric component of base commit
BASETAG=${BASE}.v1234deadbeef # whatever $(mvn -Dset.changelist validate) said
FIX=abcd1234 # as before
git checkout -b ${BASE}.x ${BASETAG}
sed -i -e 's!<version>${changelist}</version>!<version>'$BASE'.${changelist}</version>!g' {,*/}pom.xml # versions:set does not work
git commit -a -m "Prepare for ${BASE}.x"
git push -u origin ${BASE}.x
git cherry-pick -x -m1 $FIX
git push
# manually trigger release from 99.x branch