Patch copied from Gentoo removing obsolete Python2 code.

--- a/chai/chai.py
+++ b/chai/chai.py
@@ -62,11 +62,6 @@
             try:
                 func(self, *args, **kwargs)
             except UnexpectedCall as e:
-                # if this is not python3, use python2 syntax
-                if not hasattr(e, '__traceback__'):
-                    from .python2 import reraise
-                    reraise(
-                        AssertionError, '\n\n' + str(e), sys.exc_info()[-1])
                 exc = AssertionError('\n\n' + str(e))
                 setattr(exc, '__traceback__', sys.exc_info()[-1])
                 raise exc
--- a/chai/python2.py
+++ b/chai/python2.py
@@ -1,3 +0,0 @@
-
-def reraise(exc, msg, traceback):
-    raise exc, msg, traceback
--- a/chai.egg-info/SOURCES.txt
+++ b/chai.egg-info/SOURCES.txt
@@ -10,7 +10,6 @@
 chai/exception.py
 chai/expectation.py
 chai/mock.py
-chai/python2.py
 chai/spy.py
 chai/stub.py
 chai.egg-info/PKG-INFO