Bug report: 'git commit --dry-run' corner case: returns error ("nothing to commit") when all conflicts resolved to HEAD

[Ovidiu Gheorghioiu <ovidiug@gmail.com>]

Hi git guys,

The bug is fairly simple: if we have a conflicted merge, AND all the
conflicts have been resolved to the version in HEAD, the commit
--dry-run error code says nothing to commit. As expected, git commit
goes through.

The commit message IS correct (-ish), just not the error code:

"""
All conflicts fixed but you are still merging.
  (use "git commit" to conclude merge)

nothing to commit, working directory clean
"""

The script below demonstrates the problem; version tested was 2.5.0.
Let me know if you need any more details.

Best,
Ovidiu

------
#!/bin/bash
mkdir test-repository || exit 1
cd test-repository
git init
echo "Initial contents, unimportant" > test-file
git add test-file
git commit -m "Initial commit"
echo "commit-1-state" > test-file
git commit -m "commit 1" -i test-file
git tag commit-1
git checkout -b branch-2 HEAD^1
echo "commit-2-state" > test-file
git commit -m "commit 2" -i test-file

# Creates conflicted state.
git merge --no-commit commit-1

# Resolved entirely to commit-2, aka HEAD.
echo "commit-2-state" > test-file
# If we'd set to commit-1=state, all would work as expected (changes vs HEAD).
git add test-file

# =====  Bug is here.
git commit --dry-run && echo "Git said something to commit" \
        || echo "Git said NOTHING to commit"

git commit -m "Something to commit after all" && echo "Commit went through"

git log --pretty=oneline

cd ..