X wcfs: Kill xdefer

It has been properly implemented in pygolang:

pygolang@bb9a94c3

setup.py

@@ -254,7 +254,7 @@ setup(
                    #   specify either to use e.g. ZODB3.10 or ZODB4 )
                    'ZODB3 >= 3.10',
 
-                   'pygolang >= 0.0.2', # defer, sync.WaitGroup, ...
+                   'pygolang >= 0.0.5', # defer, sync.WaitGroup, ...
 
                    'six',       # compat py2/py3
 

wcfs/wcfs_test.py

@@ -1968,36 +1968,3 @@ def is_mountpoint(path):    # -> bool
 # eprint prints msg to stderr
 def eprint(msg):
     print(msg, file=sys.stderr)
-
-# xdefer is like defer, but makes sure exception raised before deferred
-# function is called is not lost.
-#
-# if deferred function raises exception itself - it prints previous exception to stderr.
-#
-# XXX xdefer is workaround for Python2 not having exception chaining (PEP 3134)
-# without which, if e.g. tDB.close() raises exception, it prevents to see
-# whether and which an assert in the test failed.
-#
-# XXX merge into defer?
-_defer = defer  # original golang.defer
-def xdefer(f):
-    # hack - imitate as if defer called from under xdefer was called directly by caller func
-    fgo = inspect.currentframe().f_back.f_back
-    __goframe__ = fgo.f_locals['__goframe__']
-    _xdefer(f)
-
-def _xdefer(f):
-    def _():
-        # call f, but print previous exception if f raises
-        exc_type, exc_value, exc_traceback = sys.exc_info()
-        try:
-            f()
-        except:
-            if exc_type is not None:
-                traceback.print_exception(exc_type, exc_value, exc_traceback)
-            raise
-    _defer(_)
-
-# replace defer with xdefer
-defer = xdefer
-del xdefer