ui-diff: action='.' is not correct

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui-diff.c

@@ -340,7 +340,7 @@ void cgit_print_diff_ctrls(void)
 
 	html("<div class='cgit-panel'>");
 	html("<b>diff options</b>");
-	html("<form method='get' action='.'>");
+	html("<form method='get'>");
 	cgit_add_hidden_formfields(1, 0, ctx.qry.page);
 	html("<table>");
 	html("<tr><td colspan='2'/></tr>");