merge with stable

convert: fix bug of wrong CVS path parsing without port number (issue3678) The cvsps.py:getrepopath suffers from a string parsing bug (it returns "user@server/path/to/repository" if the CVSROOT is given like this: ":pserver:user@server/path/to/repository" ), which gives returnes the wrong value becouse cvsps.py fails to strip the prefix from filenames. With this patch for the same input we get the correct repo path that is: "/path/to/repository"

match: add comments to explain explicitdir and traversedir

match: make explicitdir and traversedir None by default With this, extensions can easily tell when traversedir and/or explicitdir don't need to be called.

dirstate.walk: cache match.explicitdir and traversedir locally

match: drop dir callback dir has been subsumed by explicitdir and traversedir.