py3: catch PermissionError instead of checking errno == EACCES

mercurial/posix.py

@@ -302,18 +302,13 b' def checklink(path):'
                 try:
                     fullpath = os.path.join(cachedir, target)
                     open(fullpath, b'w').close()
-                except IOError as inst:
-                    # pytype: disable=unsupported-operands
-                    if inst[0] == errno.EACCES:
-                        # pytype: enable=unsupported-operands
-
+                except PermissionError:
                         # If we can't write to cachedir, just pretend
                         # that the fs is readonly and by association
                         # that the fs won't support symlinks. This
                         # seems like the least dangerous way to avoid
                         # data loss.
                         return False
-                    raise
             try:
                 os.symlink(target, name)
                 if cachedir is None: