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fix: use git branch --show-current to get branch name #252

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merged 2 commits into from
Jul 9, 2025
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fix: use git branch --show-current to get branch name #252

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89249ec
fix: use git branch --show-current to get branch name
shenxianpeng Jul 9, 2025
88ba1e4
fix: set branch name to HEAD if empty
shenxianpeng Jul 9, 2025
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5 changes: 3 additions & 2 deletions commit_check/util.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,8 +22,9 @@ def get_branch_name() -> str:
:returns: A `str` describing the current branch name.
"""
try:
commands = ['git', 'rev-parse', '--abbrev-ref', 'HEAD']
branch_name = cmd_output(commands)
# Git 2.22 and above supports `git branch --show-current`
commands = ['git', 'branch', '--show-current']
Comment on lines +25 to +26
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💡 Verification agent

🧩 Analysis chain

Verify compatibility and behavioral differences with the new Git command.

The change from git rev-parse --abbrev-ref HEAD to git branch --show-current introduces a Git version dependency (2.22+) and potential behavioral differences:

  1. Git version compatibility: Environments with Git < 2.22 will experience failures
  2. Detached HEAD behavior: git rev-parse --abbrev-ref HEAD returns "HEAD" in detached HEAD state, while git branch --show-current returns an empty string

Please verify the behavioral compatibility:

🏁 Script executed:

#!/bin/bash
# Check Git version compatibility and behavioral differences

echo "=== Git Version Check ==="
git --version

echo "=== Testing normal branch behavior ==="
# Create a test repository and branch
mkdir -p /tmp/git-test && cd /tmp/git-test
git init
git config user.email "test@example.com"
git config user.name "Test User"
echo "test" > test.txt
git add test.txt
git commit -m "Initial commit"
git checkout -b feature-branch

echo "Current branch with old command:"
git rev-parse --abbrev-ref HEAD

echo "Current branch with new command:"
git branch --show-current

echo "=== Testing detached HEAD behavior ==="
# Test detached HEAD state
git checkout HEAD~0 2>/dev/null || echo "No previous commits to detach to"

echo "Detached HEAD with old command:"
git rev-parse --abbrev-ref HEAD

echo "Detached HEAD with new command:"
git branch --show-current

# Clean up
cd / && rm -rf /tmp/git-test

Length of output: 1756

Fix Git command fallback for detached HEAD and enforce Git ≥ 2.22

The new git branch --show-current works as expected on a normal branch but:

  • In a detached HEAD state it returns an empty string (whereas git rev-parse --abbrev-ref HEAD returns "HEAD").
  • It requires Git 2.22 or newer, so older environments will fail outright.

Please update commit_check/util.py to:

  • Check git --version (or otherwise ensure Git ≥ 2.22) before using --show-current, or
  • Fall back to the old command when:
    • The version is older than 2.22, or
    • git branch --show-current yields an empty string

For example:

--- a/commit_check/util.py
+++ b/commit_check/util.py
@@ -23,7 +23,15 @@ def get_branch_name():
     """
-    # Git 2.22 and above supports `git branch --show-current`
-    commands = ['git', 'branch', '--show-current']
+    # Prefer `--show-current` on Git ≥2.22, but fallback for older versions or detached HEAD
+    def git_version_tuple():
+        v = run_cmd(['git', '--version']).strip().split()[-1]
+        return tuple(int(x) for x in v.split('.')[:2])
+
+    version = git_version_tuple()
+    cmd = ['git', 'branch', '--show-current'] if version >= (2, 22) else ['git', 'rev-parse', '--abbrev-ref', 'HEAD']
+    branch = run_cmd(cmd).strip()
+    if not branch:
+        # detached HEAD or empty result → fall back
+        branch = run_cmd(['git', 'rev-parse', '--abbrev-ref', 'HEAD']).strip()
 
     if not branch:
         raise RuntimeError("Unable to determine Git branch name")
  • Verify parsing of git --version handles major.minor correctly.
  • Ensure existing error handling remains in place.
  • Add tests for detached HEAD to confirm desired behavior.
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
# Git 2.22 and above supports `git branch --show-current`
commands = ['git', 'branch', '--show-current']
"""
# Prefer `--show-current` on Git ≥2.22, but fallback for older versions or detached HEAD
def git_version_tuple():
v = run_cmd(['git', '--version']).strip().split()[-1]
return tuple(int(x) for x in v.split('.')[:2])
version = git_version_tuple()
cmd = ['git', 'branch', '--show-current'] if version >= (2, 22) else ['git', 'rev-parse', '--abbrev-ref', 'HEAD']
branch = run_cmd(cmd).strip()
if not branch:
# detached HEAD or empty result → fall back
branch = run_cmd(['git', 'rev-parse', '--abbrev-ref', 'HEAD']).strip()
if not branch:
raise RuntimeError("Unable to determine Git branch name")
🤖 Prompt for AI Agents 
In commit_check/util.py around lines 25-26, the current use of 'git branch
--show-current' does not handle detached HEAD states and requires Git version
2.22 or newer. Modify the code to first check the installed Git version by
running 'git --version' and parsing the major and minor version numbers. Use
'git branch --show-current' only if the version is 2.22 or higher; otherwise,
fall back to 'git rev-parse --abbrev-ref HEAD'. Additionally, if 'git branch
--show-current' returns an empty string (indicating detached HEAD), also fall
back to the older command. Maintain existing error handling and add tests to
verify behavior in detached HEAD states.

branch_name = cmd_output(commands) or "HEAD"
except CalledProcessError:
branch_name = ''
return branch_name.strip()
Expand Down
4 changes: 2 additions & 2 deletions tests/util_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ def test_get_branch_name(self, mocker):
retval = get_branch_name()
assert m_cmd_output.call_count == 1
assert m_cmd_output.call_args[0][0] == [
"git", "rev-parse", "--abbrev-ref", "HEAD"
"git", "branch", "--show-current"
]
assert retval == "fake_branch_name"

Expand All @@ -45,7 +45,7 @@ def test_get_branch_name_with_exception(self, mocker):
retval = get_branch_name()
assert m_cmd_output.call_count == 1
assert m_cmd_output.call_args[0][0] == [
"git", "rev-parse", "--abbrev-ref", "HEAD"
"git", "branch", "--show-current"
]
assert retval == ""

Expand Down
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