tests/test-diff-copy-depth.t

commit: remove special handling of IOError (actually dead code)

In the past, IOError was used to mark a file as removed. The differentiation
between OSError and IOError in this place was introduced in e553a425751d, to
avoid that “normal” OSErrors / IOErrors accidentally mark files as removed.
This weird internal API was removed in 650b5b6e75ed. It seems like that
changeset should have removed the differentiation, at least I don’t see any
reason for keeping it.

On Python 3, OSError and IOError are aliased. Therefore the removed code was
actually dead.

  $ for i in aaa zzz; do
  >     hg init t
  >     cd t
  > 
  >     echo
  >     echo "-- With $i"
  > 
  >     touch file
  >     hg add file
  >     hg ci -m "Add"
  > 
  >     hg cp file $i
  >     hg ci -m "a -> $i"
  > 
  >     hg cp $i other-file
  >     echo "different" >> $i
  >     hg ci -m "$i -> other-file"
  > 
  >     hg cp other-file somename
  > 
  >     echo "Status":
  >     hg st -C
  >     echo
  >     echo "Diff:"
  >     hg diff -g
  > 
  >     cd ..
  >     rm -rf t
  > done
  
  -- With aaa
  Status:
  A somename
    other-file
  
  Diff:
  diff --git a/other-file b/somename
  copy from other-file
  copy to somename
  
  -- With zzz
  Status:
  A somename
    other-file
  
  Diff:
  diff --git a/other-file b/somename
  copy from other-file
  copy to somename