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
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<div class='path'>path: <a href='/guix/log/?id=8c801194b548d1f2d6f47dfcdd5611ae72e29759'>root</a>/<a href='/guix/log/nix?id=8c801194b548d1f2d6f47dfcdd5611ae72e29759'>nix</a>/<a href='/guix/log/nix/boost?id=8c801194b548d1f2d6f47dfcdd5611ae72e29759'>boost</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/nix/boost?id=8c801194b548d1f2d6f47dfcdd5611ae72e29759&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-06-24 19:55:22 +0100'>2020-06-24</span></td><td><a href='/guix/commit/nix/boost?id=cd43b55da7ab51c996a7a3449c78f2a493616106'>nix: Tweak .gitignore files.</a><span class='msg-avail'>...<span class='msg-tooltip'>Remove .gitignore entries where they match source files that are tracked in
Git.  This is relevant to me at least, as some code searching tools use
.gitignore files and will ignore matched files.
</span></span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2019-11-26 00:16:36 +0100'>2019-11-26</span></td><td><a href='/guix/commit/nix/boost?id=3a4d5ddd322c7daf0a8c83ca2c87c3fc38b19f0b'>daemon: boost::format: Fix typo "referred".</a><span class='msg-avail'>...<span class='msg-tooltip'>* nix/boost/format/exceptions.hpp (too_few_args): Fix typo.
  (too_many_args): Fix typo.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Vagrant Cascadian</td></tr>