tests/test-unrelated-pull.t

workingctx: eliminate remove function

Inlining it into it's last remaining call place in cmdutil.copy.

Note that cmdutil.copy is called with the wlock already held, so no additional
locking is needed to call util.unlinkpath.

We do not need to wrap the util.unlinkpath call into a try block, because
at that point we already know whether abssrc exists or not -- thanks to the
preceding util.copyfile call. Adding a new local 'srcexists' in cmdutil.copy
for that purpose.

  $ hg init a
  $ cd a
  $ echo 123 > a
  $ hg add a
  $ hg commit -m "a" -u a

  $ cd ..
  $ hg init b
  $ cd b
  $ echo 321 > b
  $ hg add b
  $ hg commit -m "b" -u b

  $ hg pull ../a
  pulling from ../a
  searching for changes
  abort: repository is unrelated
  [255]

  $ hg pull -f ../a
  pulling from ../a
  searching for changes
  warning: repository is unrelated
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg heads
  changeset:   1:9a79c33a9db3
  tag:         tip
  parent:      -1:000000000000
  user:        a
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
  changeset:   0:01f8062b2de5
  user:        b
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b