git-commit: don't add multiple Signed-off-by: from the same identity

If requested to signoff a commit, don't add another Signed-off-by: line
to the commit message if the exact same line is already there.

This was noticed and requested by Josh Triplett through
 http://bugs.debian.org/430851

Signed-off-by: Gerrit Pape <pape@smarden.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-commit.sh b/git-commit.sh
index 9106a743cc90f532be2c83d3a73799566b95df6a..f3cd8ee97839578bbfc719fd37d5b25b826623a8 100755 (executable)
--- a/git-commit.sh
+++ b/git-commit.sh
@@ -458,16 +458,18 @@ fi | git stripspace >"$GIT_DIR"/COMMIT_EDITMSG
 
 case "$signoff" in
 t)
-       need_blank_before_signoff=
+       sign=$(git-var GIT_COMMITTER_IDENT | sed -e '
+               s/>.*/>/
+               s/^/Signed-off-by: /
+               ')
+       blank_before_signoff=
        tail -n 1 "$GIT_DIR"/COMMIT_EDITMSG |
-       grep 'Signed-off-by:' >/dev/null || need_blank_before_signoff=yes
-       {
-               test -z "$need_blank_before_signoff" || echo
-               git-var GIT_COMMITTER_IDENT | sed -e '
-                       s/>.*/>/
-                       s/^/Signed-off-by: /
-               '
-       } >>"$GIT_DIR"/COMMIT_EDITMSG
+       grep 'Signed-off-by:' >/dev/null || blank_before_signoff='
+'
+       tail -n 1 "$GIT_DIR"/COMMIT_EDITMSG |
+       grep "$sign"$ >/dev/null ||
+       printf '%s%s\n' "$blank_before_signoff" "$sign" \
+               >>"$GIT_DIR"/COMMIT_EDITMSG
        ;;
 esac