+# This could be traditional "merge <msg> HEAD <commit>..." and the
+# way we can tell it is to see if the second token is HEAD, but some
+# people might have misused the interface and used a committish that
+# is the same as HEAD there instead. Traditional format never would
+# have "-m" so it is an additional safety measure to check for it.
+
+if test -z "$have_message" &&
+ second_token=$(git-rev-parse --verify "$2^0" 2>/dev/null) &&
+ head_commit=$(git-rev-parse --verify "HEAD" 2>/dev/null) &&
+ test "$second_token" = "$head_commit"
+then
+ merge_msg="$1"
+ shift
+ head_arg="$1"
+ shift
+else
+ # We are invoked directly as the first-class UI.
+ head_arg=HEAD
+
+ # All the rest are the commits being merged; prepare
+ # the standard merge summary message to be appended to
+ # the given message. If remote is invalid we will die
+ # later in the common codepath so we discard the error
+ # in this loop.
+ merge_name=$(for remote
+ do
+ rh=$(git-rev-parse --verify "$remote"^0 2>/dev/null)
+ if git show-ref -q --verify "refs/heads/$remote"
+ then
+ what=branch
+ else
+ what=commit
+ fi
+ echo "$rh $what '$remote'"
+ done | git-fmt-merge-msg
+ )
+ merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
+fi
+head=$(git-rev-parse --verify "$head_arg"^0) || usage