In r62273 (Apr 2008), method testAsyncoreServer() was added to the py3k branch with indata="FOO\n". In r64578 (Jun 2008), this test method was added to the Py 2 branch, but with indata = "TEST MESSAGE of mixed case\n". Later, r80598 added the mixed case line to the Py 3 branch, but it is not used because the original FOO line overwrites it. Then revision 221a1f9155e2 backported the Py 3 code to 2.7. So now both versions include the mixed case line but neither use it.

I haven’t investigated, but I presume either the mixed case version would test more stuff and should be enabled, or it would be overkill and should be dropped in favour of the simpler line.