py3: raise exceptions using six module

There is no other way to make Python2 and Python3 happy, because syntax
raise E, V, T is incompatible with the latter.

Signed-off-by: Łukasz Żarnowiecki <dolohow@outlook.com>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

offlineimap/CustomConfig.py

@@ -18,6 +18,8 @@ import os
 import re
 from sys import exc_info
 
+import six
+
 try:
     from ConfigParser import SafeConfigParser, Error
 except ImportError: #python3
@@ -75,8 +77,8 @@ class CustomConfigParser(SafeConfigParser):
             val = self.get(section, option).strip()
             return re.split(separator_re, val)
         except re.error as e:
-            raise Error("Bad split regexp '%s': %s" % \
-              (separator_re, e)), None, exc_info()[2]
+            six.reraise(Error("Bad split regexp '%s': %s" % \
+              (separator_re, e)), None, exc_info()[2])
 
     def getdefaultlist(self, section, option, default, separator_re):
         """Same as getlist, but returns the value of `default`