tests/test-strict.t

py3: fix curses chunkselector fallback (when diffs are too large) on py3

Previously we showed the message using Exception.message, which is removed in
py3. Since crecordmod.fallbackerror inherits from error.Abort, we can just use
`b'%s' % exception` to print the message. This does not print the hint, but
that's fine - we don't set one. We inherit from error.Abort so that if a
codepath doesn't handle fallback specially, it exits to the terminal with a sane
message instead of an unknown exception error.

Differential Revision: https://phab.mercurial-scm.org/D7912

  $ hg init

  $ echo a > a
  $ hg ci -Ama
  adding a

  $ hg an a
  0: a

  $ hg --config ui.strict=False an a
  0: a

  $ echo "[ui]" >> $HGRCPATH
  $ echo "strict=True" >> $HGRCPATH

  $ hg an a
  hg: unknown command 'an'
  (use 'hg help' for a list of commands)
  [255]
  $ hg annotate a
  0: a

should succeed - up is an alias, not an abbreviation

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