Revert "Patch os.chdir to raise an exception, once twistd is done wit…

…h it"

This reverts commit 4f6d211.

Patching os.chdir causes subprocess to fail in the child.  Too bad :(

Refs #1007

master/buildbot/master.py

@@ -15,8 +15,8 @@
 from twisted.application.internet import TimerService
 
 import buildbot
+# sibling imports
 from buildbot.util import now, safeTranslate, eventual
-from buildbot.util import monkeypatches
 from buildbot.pbutil import NewCredPerspective
 from buildbot.process.builder import Builder, IDLE
 from buildbot.status.builder import Status, BuildSetStatus
@@ -571,10 +571,6 @@ def startService(self):
             b.builder_status.addPointEvent(["master", "started"])
             b.builder_status.saveYourself()
 
-        # now that we're running a master, don't use os.chdir.  Note that this
-        # will trip up twistd if we do it any earlier
-        monkeypatches.disable_os_chdir()
-
     def _handleSIGHUP(self, *args):
         reactor.callLater(0, self.loadTheConfigFile)
 

master/buildbot/util/monkeypatches.py

@@ -1,11 +1,5 @@
-import os
 from twisted.trial import unittest
 
-def disable_os_chdir():
-    def DoNotUseOsChDir(_):
-      raise ValueError('Do not use os.chdir() in your code.  You probably want to use path=foo or cwd=foo argument when calling out subprocesses instead')
-    os.chdir = DoNotUseOsChDir
-
 def add_debugging_monkeypatches():
     """
     DO NOT CALL THIS DIRECTLY