bash_completion: allow remove to complete normal files

Previously, we only completed files that had already been manually
deleted. That behaviour made no sense. We now complete unmodified,
modified, and deleted files.
bash_completion: tell an editor what type of file this is
test-archive: gracefully handle HTTPErrors on get-with-headers

This avoids pritting out a traceback when a get-with-headers call causes hgweb
to respond with an HTTPError code.

--HG--
extra : rebase_source : f454687c6e2329bb833cf245c9f9d9ac33144652