tests/test-dirstate-backup.t

hgweb: expose URL scheme and REMOTE_* attributes

These are consulted by the HTTP wire protocol handler by reading from
the env dict. Let's expose them as attributes instead.

With the wire protocol handler updates to use the new attributes, we
no longer have any consumers of the legacy wsgirequest type in the
wire protocol code (outside of a proxied call to the permissions
checker). So, we remove most references to it.

Differential Revision: https://phab.mercurial-scm.org/D2783

Set up

  $ hg init repo
  $ cd repo

Try to import an empty patch

  $ hg import --no-commit - <<EOF
  > EOF
  applying patch from stdin
  abort: stdin: no diffs found
  [255]

No dirstate backups are left behind

  $ ls .hg/dirstate* | sort
  .hg/dirstate