[gcc(refs/users/guojiufu/heads/guojiufu-branch)] contrib: Make prepare-commit-msg hook safe for older branches

[Jiu Fu Guo]

https://gcc.gnu.org/g:9127b5239871fb1e16f26abb17081599b38a4d53

commit 9127b5239871fb1e16f26abb17081599b38a4d53
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Jun 2 11:18:21 2020 +0100

    contrib: Make prepare-commit-msg hook safe for older branches
    
    If a user installs this script as .git/hooks/prepare-commit-msg and then
    works on an old branch which doesn't have the mklog.py script, trying to
    commit will fail with an error like:
    
    environment: /.../gcc/contrib/mklog.py: No such file or directory
    
    This makes it exit cleanly so it's possible to commit.
    
    contrib/ChangeLog:
    
            * prepare-commit-msg: Do nothing if the mklog.py script isn't
            present.

Diff:
---
 contrib/prepare-commit-msg | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/contrib/prepare-commit-msg b/contrib/prepare-commit-msg
index fd59bfbcf88..24f0783aae2 100755
--- a/contrib/prepare-commit-msg
+++ b/contrib/prepare-commit-msg
@@ -23,6 +23,9 @@ COMMIT_MSG_FILE=$1
 COMMIT_SOURCE=$2
 SHA1=$3
 
+# We might be on a branch before the file was added.
+if ! [ -x contrib/mklog.py ]; then exit 0; fi
+
 # Can't do anything if $COMMIT_MSG_FILE isn't a file.
 if ! [ -f "$COMMIT_MSG_FILE" ]; then exit 0; fi