tests/test-absorb-unfinished.t

setup: drop the hack to disable linker warning 4197 on Windows

I don't see this when building on Windows with py3.8 or py3.12, so either the
code was fixed, or (more likely) the compiler stopped warning about it some time
after VS 2008.  If we do have to put this back, it would probably be better to
put a `#pragma` in a header file somewhere, and avoid `setuptools` technical
debt.

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > absorb=
  > EOF

Abort absorb if there is an unfinished operation.

  $ hg init abortunresolved
  $ cd abortunresolved

  $ echo "foo1" > foo.whole
  $ hg commit -Aqm "foo 1"

  $ hg update null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo "foo2" > foo.whole
  $ hg commit -Aqm "foo 2"

  $ hg --config extensions.rebase= rebase -r 1 -d 0
  rebasing 1:c3b6dc0e177a tip "foo 2"
  merging foo.whole
  warning: conflicts while merging foo.whole! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

  $ hg --config extensions.rebase= absorb
  abort: rebase in progress
  (use 'hg rebase --continue', 'hg rebase --abort', or 'hg rebase --stop')
  [20]