tests/test-update-issue1456.t

rebase: improve error message on improper phases

The previous error message had two issues: The first issue was that it
wasn't, in fact, an error but a warning, even though it described a
fatal error condition preventing the successful completion of the
command. The second was that it didn't mention the immutable
changesets, leaving the user guessing at the true cause of the error.

The main downside to this change is that we now get an 'abort: can't
abort...' message which technically contradicts itself. In this case,
I blame that on the two uses we have for the word; if it weren't for
backwards compatibility, we could make util.Abort print out 'error:
<whatever>'.

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

  $ rm -rf a
  $ hg init a
  $ cd a

  $ echo foo > foo
  $ hg ci -qAm0
  $ chmod +x foo
  $ hg ci -m1
  $ hg co -q 0
  $ echo dirty > foo
  $ hg up -c
  abort: uncommitted local changes
  [255]
  $ hg up -q
  $ cat foo
  dirty
  $ hg st -A
  M foo

Validate update of standalone execute bit change:

  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ chmod -x foo
  $ hg ci -m removeexec
  nothing changed
  [1]
  $ hg up -C 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg up
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg st