prepare-commit-hook: Use gcc-config.diff-file.

contrib/ChangeLog:

	* prepare-commit-msg: Replace ENV variable with a git config
	value.

diff --git a/contrib/prepare-commit-msg b/contrib/prepare-commit-msg
index 57bb917..cc9ba2e 100755 (executable)
--- a/contrib/prepare-commit-msg
+++ b/contrib/prepare-commit-msg
@@ -58,8 +58,9 @@ else
 fi
 
 # Save diff to a file if requested.
-if ! [ -z "$GCC_GIT_DIFF_FILE" ]; then
-    tee="tee $GCC_GIT_DIFF_FILE"
+DIFF_FILE=$(git config gcc-config.diff-file)
+if ! [ -z "$DIFF_FILE" ]; then
+    tee="tee $DIFF_FILE"
 else
     tee="cat"
 fi