interpret_nth_last_branch(): avoid traversing the reflog twice

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 89c39ebc9df58a85011219dff21ffac9dd6a53ab..8ed2244819d0950ddf1ffaa151b4d46bdc8b6db4 100755 (executable)
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -115,9 +115,18 @@ mark_action_done () {
 }
 
 make_patch () {
-       parent_sha1=$(git rev-parse --verify "$1"^) ||
-               die "Cannot get patch for $1^"
-       git diff-tree -p "$parent_sha1".."$1" > "$DOTEST"/patch
+       sha1_and_parents="$(git rev-list --parents -1 "$1")"
+       case "$sha1_and_parents" in
+       ?*' '?*' '?*)
+               git diff --cc $sha1_and_parents
+               ;;
+       ?*' '?*)
+               git diff-tree -p "$1^!"
+               ;;
+       *)
+               echo "Root commit"
+               ;;
+       esac > "$DOTEST"/patch
        test -f "$DOTEST"/message ||
                git cat-file commit "$1" | sed "1,/^$/d" > "$DOTEST"/message
        test -f "$DOTEST"/author-script ||
@@ -340,7 +349,7 @@ do_next () {
        squash|s)
                comment_for_reflog squash
 
-               has_action "$DONE" ||
+               test -f "$DONE" && has_action "$DONE" ||
                        die "Cannot 'squash' without a previous commit"
 
                mark_action_done