Example with GIT_TRACE=1 and GIT_CURL_VERBOSE=1...

gistfile1.txt

:: GIT_TRACE=1 GIT_CURL_VERBOSE=1 git clone https://github.com/google/breakpad.git
06:59:28.873440 git.c:344               trace: built-in: git 'clone' 'https://github.com/google/breakpad.git'
Cloning into 'breakpad'...
06:59:28.892350 run-command.c:627       trace: run_command: 'git-remote-https' 'origin' 'https://github.com/google/breakpad.git'
* Couldn't find host github.com in the .netrc file; using defaults
*   Trying 192.30.253.112...
* TCP_NODELAY set
* Connected to github.com (192.30.253.112) port 443 (#0)
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/cert.pem
  CApath: none
* SSL connection using TLSv1.2 / ECDHE-RSA-AES128-GCM-SHA256
* ALPN, server accepted to use http/1.1
* Server certificate:
*  subject: businessCategory=Private Organization; 1.3.6.1.4.1.311.60.2.1.3=US; 1.3.6.1.4.1.311.60.2.1.2=Delaware; serialNumber=5157550; street=88 Colin P Kelly, Jr Street; postalCode=94107; C=US; ST=California; L=San Francisco; O=GitHub, Inc.; CN=github.com
*  start date: Mar 10 00:00:00 2016 GMT
*  expire date: May 17 12:00:00 2018 GMT
*  subjectAltName: host "github.com" matched cert's "github.com"
*  issuer: C=US; O=DigiCert Inc; OU=www.digicert.com; CN=DigiCert SHA2 Extended Validation Server CA
*  SSL certificate verify ok.
> GET /google/breakpad.git/info/refs?service=git-upload-pack HTTP/1.1
Host: github.com
User-Agent: git/2.16.1
Accept: */*
Accept-Encoding: gzip
Pragma: no-cache

< HTTP/1.1 200 OK
< Server: GitHub Babel 2.0
< Content-Type: application/x-git-upload-pack-advertisement
< Transfer-Encoding: chunked
< Expires: Fri, 01 Jan 1980 00:00:00 GMT
< Pragma: no-cache
< Cache-Control: no-cache, max-age=0, must-revalidate
< Vary: Accept-Encoding
< X-GitHub-Request-Id: F8C2:2BD5:9EFF59:1046865:5A7AEA20
< X-Frame-Options: DENY
<
* Connection #0 to host github.com left intact
06:59:29.084514 run-command.c:627       trace: run_command: 'fetch-pack' '--stateless-rpc' '--stdin' '--lock-pack' '--thin' '--check-self-contained-and-connected' '--cloning' 'https://github.com/google/breakpad.git/'
06:59:29.091055 git.c:344               trace: built-in: git 'fetch-pack' '--stateless-rpc' '--stdin' '--lock-pack' '--thin' '--check-self-contained-and-connected' '--cloning' 'https://github.com/google/breakpad.git/'
* Couldn't find host github.com in the .netrc file; using defaults
* Found bundle for host github.com: 0x7f8e9f402180 [can pipeline]
* Re-using existing connection! (#0) with host github.com
* Connected to github.com (192.30.253.112) port 443 (#0)
> POST /google/breakpad.git/git-upload-pack HTTP/1.1
Host: github.com
User-Agent: git/2.16.1
Accept-Encoding: gzip
Content-Type: application/x-git-upload-pack-request
Accept: application/x-git-upload-pack-result
Content-Length: 965

* upload completely sent off: 965 out of 965 bytes
< HTTP/1.1 200 OK
< Server: GitHub Babel 2.0
< Content-Type: application/x-git-upload-pack-result
< Transfer-Encoding: chunked
< Expires: Fri, 01 Jan 1980 00:00:00 GMT
< Pragma: no-cache
< Cache-Control: no-cache, max-age=0, must-revalidate
< Vary: Accept-Encoding
< X-GitHub-Request-Id: F8C2:2BD5:9EFF6F:1046877:5A7AEA21
< X-Frame-Options: DENY
<
remote: Counting objects: 17372, done.
remote: Compressing objects: 100% (22/22), done.
06:59:29.172273 run-command.c:627       trace: run_command: 'index-pack' '--stdin' '-v' '--fix-thin' '--keep=fetch-pack 24952 on sidious.home' '--check-self-contained-and-connected' '--pack_header=2,17372' '--strict'
06:59:29.177014 git.c:344               trace: built-in: git 'index-pack' '--stdin' '-v' '--fix-thin' '--keep=fetch-pack 24952 on sidious.home' '--check-self-contained-and-connected' '--pack_header=2,17372' '--strict'
* Connection #0 to host github.com left intactiB | 5.78 MiB/s
remote: Total 17372 (delta 14), reused 20 (delta 9), pack-reused 17341
Receiving objects: 100% (17372/17372), 39.46 MiB | 5.84 MiB/s, done.
Resolving deltas: 100% (13600/13600), done.
06:59:36.285567 run-command.c:627       trace: run_command: 'rev-list' '--objects' '--stdin' '--not' '--all' '--quiet' '--progress=Checking connectivity'
06:59:36.296333 git.c:344               trace: built-in: git 'rev-list' '--objects' '--stdin' '--not' '--all' '--quiet' '--progress=Checking connectivity'