tests/test-issue1438.t

wireproto: add out-of-band error class to allow remote repo to report errors

Older clients will still print the provided error message and not much else:
over ssh, this will be each line prefixed with 'remote: ' in addition to an
"abort: unexpected response: '\n'"; over http, this will be the '---%<---'
banners in addition to the 'does not appear to be a repository' message.

Currently, clients with this patch will display 'abort: remote error:\n' and
the provided error text, but it is trivial to style the error text however is
deemed appropriate.

http://mercurial.selenic.com/bts/issue1438

  $ "$TESTDIR/hghave" symlink || exit 80

  $ hg init

  $ ln -s foo link
  $ hg add link
  $ hg ci -mbad link
  $ hg rm link
  $ hg ci -mok
  $ hg diff -g -r 0:1 > bad.patch

  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg import --no-commit bad.patch
  applying bad.patch

  $ hg status
  R link
  ? bad.patch