hghave: detect cvs and cvsps availability
"cvsps -h" was returning 1 in cygwin, probably because CVSROOT was unset, which does not prevent it to work correctly.
parents: make it match the doc when called on a file
parents used to return the parent revision of the last revision updating selected file, instead of the updating revision itself.
mq: fix regression in
6fd953d5faea
It caused qrefresh; qrefresh -X addedfile to leave the file as normal in dirstate.
It should be marked added on the second pass.