tests: new test cases for the unbundlehash capability

copy: do not copy file if name is disallowed anyway

util: new function checkfilename checkfilename checks for restrictions on filenames imposed by Mercurial itself, irrespective of on what platform it is run.

opener: use %r in format string for abort

wireproto: allow unbundle with hashed heads parameter (issue2126) Current wire protocol of unbundle sends the list of all heads in the remote repository to avoid race condition. This causes "URL too long" error on HTTP server when the repository has many heads. This change allows clients to send SHA1 hash of sorted head hashes instead. Also, this introduces "unbundlehash" capability to inform them that the server accepts hashed heads parameter.

merge with stable

encoding: avoid localstr when a string can be encoded losslessly (issue2763) localstr's hash method exists to prevent bogus matching on lossy local encodings. For instance, we don't want 'caf?' to match 'café' in an ASCII locale. But when café can be losslessly encoded in the local charset, we can simply use a normal string and avoid the hashing trick. This avoids using localstr's hash method, which would prevent a match between

merge with stable

revset: optimize stringset when subset == entire repo if range(len(repo)) is passed to stringset and x is a valid rev (checked before) then x is guaranteed to be in subset, we can check for that by comparing the lengths of the sets

help/revset: fix grammar