Fix an infinite loop in sq_quote_buf().

sq_quote_buf() treats single-quotes and exclamation marks specially, but
it incorrectly parsed the input for single-quotes and backslashes.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

quote.c

@@ -26,7 +26,7 @@ void sq_quote_buf(struct strbuf *dst, const char *src)
 
 	strbuf_addch(dst, '\'');
 	while (*src) {
-		size_t len = strcspn(src, "'\\");
+		size_t len = strcspn(src, "'!");
 		strbuf_add(dst, src, len);
 		src += len;
 		while (need_bs_quote(*src)) {

t/t5510-fetch.sh

@@ -208,4 +208,11 @@ test_expect_success 'fetch with a non-applying branch.<name>.merge' '
 	git fetch blub
 '
 
+# the strange name is: a\!'b
+test_expect_success 'quoting of a strangely named repo' '
+	! git fetch "a\\!'\''b" > result 2>&1 &&
+	cat result &&
+	grep "fatal: '\''a\\\\!'\''b'\''" result
+'
+
 test_done