[Cogito] Various bugs

A few Cogito bugs I found yesterday.

 - cg-fetch between local repos fails when the cloned branch URL does
   not point to a .git directory and a needed object from the repository
   being cloned is packed. git-local-fetch expects a .git directory.

 - cg-commit -c will do the wrong thing (use the invokers gecos info)
   when the author name is empty. One workaround is to make
   pick_author_script append a space at the end of the GIT_* variables.
   GIT will strip those and no gecos info is used.

 - cg-status reports a deleted file both as deleted and as unknown:

	fonseca@antimatter:~/src/elinks/0.12 > git --version
	git version 1.1.6.g1506
	fonseca@antimatter:~/src/elinks/0.12 > cg --version
	cogito-0.17pre.GIT (d3aa9a2b3375e36c774ea477492db76baa1db03e)
	fonseca@antimatter:~/src/elinks/0.12 > cg rm AUTHORS
	Removing file AUTHORS
	fonseca@antimatter:~/src/elinks/0.12 > cg status | grep AUTHORS
	? AUTHORS
	D AUTHORS

-- 
Jonas Fonseca