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.

mercurial/commit.py

@@ -4,8 +4,6 b''
 # GNU General Public License version 2 or any later version.
 
 
-import errno
-
 from .i18n import _
 from .node import (
     hex,
@@ -250,11 +248,6 b' def _process_files(tr, ctx, ms, files, n'
         except OSError:
             repo.ui.warn(_(b"trouble committing %s!\n") % uipathfn(f))
             raise
-        except IOError as inst:
-            errcode = getattr(inst, 'errno', errno.ENOENT)
-            if error or errcode and errcode != errno.ENOENT:
-                repo.ui.warn(_(b"trouble committing %s!\n") % uipathfn(f))
-            raise
 
     # update manifest
     removed = [f for f in removed if f in m1 or f in m2]