largefiles: fix commit when using relative paths from subdirectory
Remove cwd handling from getstandinmatcher - it did not belong there, as proven
by the tests.
largefiles: allow use of urls with #revision
largefiles tried to create a peer directly with the specified url. That caused
abort: unsupported URL component: "..."
if a revision was specified in the url.
The branch name do not matter for largefiles' use of remote peers. Largefiles
will be shared among all branches anyway.