merge with mainline

do not disclose proxy user and password in debug messages

merge: minor nullid cleanup

context: add __nonzero__ methods

merge: use repo.parents and parent contexts in update

Add str methods to contexts

Add equality operators to changectx and filectx

localrepo.parents: return null context for no parents

Add localrepo.parents to get parent changectxs.

merge: move partial filtering out of manifest merge

merge: move findcopies after workingmanifest

findcopies: shortcut for empty working dir

fix users of dirstate.copies broken by b1f10d3223c1

Merge with crew

optimize revlog.lookup when passed hex(node)[:...] Instead of converting each node from the filenode to a hex form, convert the arg to a bin form. For a revlog with 26711 entries, doing 100 lookup: before: ~18s after : ~13s