revert(3p/git): Revert merge of git upstream at v2.26.2

This causes cgit to serve error pages, which is undesirable.

This reverts commit 5229c9b232, reversing
changes made to f2b211131f.

third_party/git/transport-internal.h

@@ -6,6 +6,12 @@ struct transport;
 struct argv_array;
 
 struct transport_vtable {
+	/**
+	 * This transport supports the fetch() function being called
+	 * without get_refs_list() first being called.
+	 */
+	unsigned fetch_without_list : 1;
+
 	/**
 	 * Returns 0 if successful, positive if the option is not
 	 * recognized or is inapplicable, and negative if the option