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
b right'></td></tr></table>
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<div class='path'>path: <a href='/guix/log/?id=ebf07a06f0a29eac6b5f115b10fc1eb7574f060c'>root</a>/<a href='/guix/log/tests?id=ebf07a06f0a29eac6b5f115b10fc1eb7574f060c'>tests</a>/<a href='/guix/log/tests/guix-authenticate.sh?id=ebf07a06f0a29eac6b5f115b10fc1eb7574f060c'>guix-authenticate.sh</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/guix-authenticate.sh?id=ebf07a06f0a29eac6b5f115b10fc1eb7574f060c&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-09-15 14:40:20 +0200'>2020-09-15</span></td><td><a href='/guix/commit/tests/guix-authenticate.sh?id=b911d6547444b5f8d17b224bafa5ee1b5aafaff5'>authenticate: Encode strings as ISO-8859-1.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-09-14 15:42:55 +0200'>2020-09-14</span></td><td><a href='/guix/commit/tests/guix-authenticate.sh?id=64cf660f872fb7aaf0d2b463e45b4c756297f743'>daemon: Spawn 'guix authenticate' once for all.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-09-11 17:53:58 +0200'>2020-09-11</span></td><td><a href='/guix/commit/tests/guix-authenticate.sh?id=6dd8ffc57420ee2f6f19e79e41028e78fe9e6a7e'>daemon: Simplify interface with 'guix authenticate'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>