pull: handle --log=<n>

Since efb779f (merge, pull: add '--(no-)log' command line option,
2008-04-06) git-pull supported the (--no-)log switch and would pass it
to git-merge.

96e9420 (merge: Make '--log' an integer option for number of shortlog
entries, 2010-09-08) implemented support for the --log=<n> switch, which
would explicitly set the number of shortlog entries. However, git-pull
does not recognize this option, and will instead pass it to git-fetch,
leading to "unknown option" errors.

Fix this by matching --log=* in addition to --log and --no-log.

Implement a test for this use case.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t5524-pull-msg.sh b/t/t5524-pull-msg.sh
index 8cccecc..c278ada 100755
--- a/t/t5524-pull-msg.sh
+++ b/t/t5524-pull-msg.sh
@@ -17,6 +17,9 @@
 		git commit -m "add bfile"
 	) &&
 	test_tick && test_tick &&
+	echo "second" >afile &&
+	git add afile &&
+	git commit -m "second commit" &&
 	echo "original $dollar" >afile &&
 	git add afile &&
 	git commit -m "do not clobber $dollar signs"
@@ -32,4 +35,18 @@
 )
 '
 
+test_expect_success '--log=1 limits shortlog length' '
+(
+	cd cloned &&
+	git reset --hard HEAD^ &&
+	test "$(cat afile)" = original &&
+	test "$(cat bfile)" = added &&
+	git pull --log=1 &&
+	git log -3 &&
+	git cat-file commit HEAD >result &&
+	grep Dollar result &&
+	! grep "second commit" result
+)
+'
+
 test_done