nhed/drop-commit-alias-tests.md

## drop-commit-alias-tests.md

      
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              drop-commit-alias-tests.md
            
          
    Scratching my head regarding an answer on stackoverflow https://stackoverflow.com/a/69949813/652904
Setup

$ for x in {1..9}; do echo "${x}" > "${x}.txt"; git add "${x}.txt"; git commit -m "Adding ${x}.txt"; done
[dummy fc791a8] Adding 1.txt
 1 file changed, 1 insertion(+)
 create mode 100644 1.txt
[dummy c060042] Adding 2.txt
 1 file changed, 1 insertion(+)
 create mode 100644 2.txt
[dummy 3e57b24] Adding 3.txt
 1 file changed, 1 insertion(+)
 create mode 100644 3.txt
[dummy 6bf3d29] Adding 4.txt
 1 file changed, 1 insertion(+)
 create mode 100644 4.txt
[dummy d5047a3] Adding 5.txt
 1 file changed, 1 insertion(+)
 create mode 100644 5.txt
[dummy 07e264a] Adding 6.txt
 1 file changed, 1 insertion(+)
 create mode 100644 6.txt
[dummy 14b5a8d] Adding 7.txt
 1 file changed, 1 insertion(+)
 create mode 100644 7.txt
[dummy eeebb3f] Adding 8.txt
 1 file changed, 1 insertion(+)
 create mode 100644 8.txt
[dummy 805e990] Adding 9.txt
 1 file changed, 1 insertion(+)
 create mode 100644 9.txt

Yielding
$ git log --pretty=oneline --abbrev-commit origin/main..HEAD
805e990 (HEAD -> dummy) Adding 9.txt
eeebb3f Adding 8.txt
14b5a8d Adding 7.txt
07e264a Adding 6.txt
d5047a3 Adding 5.txt
6bf3d29 Adding 4.txt
3e57b24 Adding 3.txt
c060042 Adding 2.txt
fc791a8 Adding 1.txt

First try both forms in bash

With && : (dropping 3.txt)

$ git rebase --onto 3e57b24^ 3e57b24 && :
Successfully rebased and updated refs/heads/dummy.

$ git log --pretty=oneline --abbrev-commit origin/main..HEAD
ccfd21f (HEAD -> dummy) Adding 9.txt
3c0a22f Adding 8.txt
9ab6818 Adding 7.txt
5466ebc Adding 6.txt
15a93e2 Adding 5.txt
ddaf52d Adding 4.txt
c060042 Adding 2.txt
fc791a8 Adding 1.txt

Without && : (dropping 4.txt)

$ git rebase --onto ddaf52d^ ddaf52d
Successfully rebased and updated refs/heads/dummy.

$ git log --pretty=oneline --abbrev-commit origin/main..HEAD
5d943c7 (HEAD -> dummy) Adding 9.txt
7d90139 Adding 8.txt
30058d0 Adding 7.txt
bb3e237 Adding 6.txt
7c909b0 Adding 5.txt
c060042 Adding 2.txt
fc791a8 Adding 1.txt

So far so good!
With the following 2 git aliases

$ grep drop-commit- ~/.gitconfig
  drop-commit-without = !git rebase --onto $1^ $1
  drop-commit-with = !git rebase --onto $1^ $1 && :

With && : (dropping 5.txt)

$ git drop-commit-with 7c909b0
Successfully rebased and updated refs/heads/dummy.

$ git log --pretty=oneline --abbrev-commit origin/main..HEAD
5b560df (HEAD -> dummy) Adding 9.txt
cee9f09 Adding 8.txt
2a1dae3 Adding 7.txt
11a7733 Adding 6.txt
c060042 Adding 2.txt
fc791a8 Adding 1.txt

Without && : (trying to drop 6.txt)

$ git drop-commit-without 11a7733
Successfully rebased and updated detached HEAD.

$ git log --pretty=oneline --abbrev-commit origin/main..HEAD
c060042 (HEAD) Adding 2.txt
fc791a8 Adding 1.txt

Instead of just dropping #6 it dropped #6, #7 & #8!
So I'm really curious what does && : do here because in classical bash : is a
no-op and I'm used to using it with || to skip an error (say if set -e was in
effect or in a makefile rule - but no idea what it's purpose is with && or if it
has special meaning in git-config