[PATCH] Generic support for pulling refs

This adds support to pull.c for requesting a reference and writing it to a
file. All of the git-*-pull programs get stubs for now.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

pull.h

@@ -4,6 +4,14 @@
 /** To be provided by the particular implementation. **/
 extern int fetch(unsigned char *sha1);
 
+extern int fetch_ref(char *ref, unsigned char *sha1);
+
+/** If set, the ref filename to write the target value to. **/
+extern const char *write_ref;
+
+/** If set, the hash that the current value of write_ref must be. **/
+extern const unsigned char *current_ref;
+
 /** Set to fetch the target tree. */
 extern int get_tree;