Introduce a new revision set operator <rev>^!

This is a shorthand for "<rev> --not <rev>^@", i.e. "include
this commit but exclude any of its parents".

When a new file $F is introduced by revision $R, this notation
can be used to find a copy-and-paste from existing file in the
parents of that revision without annotating the ancestry of the
lines that were copied from:

	git pickaxe -f -C $R^! -- $F

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

1 files changed, 7 insertions, 0 deletions

diff --git a/revision.c b/revision.c
index f1e0caaae3..b021d3354e 100644
--- a/revision.c
+++ b/revision.c
@@ -660,6 +660,13 @@ int handle_revision_arg(const char *arg, struct rev_info *revs,
 			return 0;
 		*dotdot = '^';
 	}
+	dotdot = strstr(arg, "^!");
+	if (dotdot && !dotdot[2]) {
+		*dotdot = 0;
+		if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
+			*dotdot = '^';
+	}
+
 	local_flags = 0;
 	if (*arg == '^') {
 		local_flags = UNINTERESTING;