git-am: do not allow empty commits by mistake.

Running "git-am --resolved" without doing anything can create an empty
commit. Prevent it.

Thanks for Eric W. Biederman for spotting this.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/git-am.sh b/git-am.sh
index 85ecada..7cc4ae5 100755 (executable)
--- a/git-am.sh
+++ b/git-am.sh
@@ -300,7 +300,7 @@ do
            } >"$dotest/final-commit"
            ;;
        *)
-               case "$resolved,$interactive" in
+               case "$resolved$interactive" in
                tt)
                        # This is used only for interactive view option.
                        git-diff-index -p --cached HEAD >"$dotest/patch"
@@ -364,6 +364,12 @@ do
                # trust what the user has in the index file and the
                # working tree.
                resolved=
+               changed="$(git-diff-index --cached --name-only HEAD)"
+               if test '' = "$changed"
+               then
+                       echo "No changes - did you forget update-index?"
+                       stop_here $this
+               fi
                apply_status=0
                ;;
        esac
@@ -374,7 +380,7 @@ do
                then
                    # Applying the patch to an earlier tree and merging the
                    # result may have produced the same tree as ours.
-                   changed="$(git-diff-index --cached --name-only -z HEAD)"
+                   changed="$(git-diff-index --cached --name-only HEAD)"
                    if test '' = "$changed"
                    then
                            echo No changes -- Patch already applied.