refspec: make @ a synonym of HEAD

Since commit 9ba89f484e git learned how to push to a remote branch using
the source @, for example:

  git push origin @:master

However, if the right-hand side is missing, the push fails:

  git push origin @

It is obvious what is the desired behavior, and allowing the push makes
things more consistent.

Additionally, @:master now has the same semantics as HEAD:master.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/refspec.c b/refspec.c
index c49347c..adbfb32 100644
--- a/refspec.c
+++ b/refspec.c
@@ -71,7 +71,10 @@ static int parse_refspec(struct refspec_item *item, const char *refspec, int fet
 	}
 
 	item->pattern = is_glob;
-	item->src = xstrndup(lhs, llen);
+	if (llen == 1 && *lhs == '@')
+		item->src = xstrdup("HEAD");
+	else
+		item->src = xstrndup(lhs, llen);
 	flags = REFNAME_ALLOW_ONELEVEL | (is_glob ? REFNAME_REFSPEC_PATTERN : 0);
 
 	if (item->negative) {