parse_qsl function from _apachemodule.c compiled with python3 raises Segmentation fault while parsing some key-value pair #87

I compiled mod_python with python3

In order to get python3 linked with mod_python.so, I applied changes present in pull reqest : #86

with python linked to mod_python.so I was able to run mod_python and python related APIs.
However parse_qsl function present in src/_apachemodule.c seems to fail for some key-value pairs(where key contains underscore).

Here is what I did:
I added pdb (python debugger) to lib/python/mod_python/util.py at line 251.

And I ran apache on foreground with debug option enabled using gdb
following is the command I used to run apache on foreground with debug mode
gdb --args /usr/sbin/apache2 -X -k start

when I hit the url, I entered pdb session where I called parse_qsl with various parameters
following is the console output.

> /usr/local/lib/python3.5/dist-packages/mod_python/util.py(254)__init__()
-> if req.args:
(Pdb) l
249
250             self.list = FieldList()
251
252             # always process GET-style parameters
253             pdb.set_trace()
254  ->         if req.args:
255                 pairs = parse_qsl(req.args, keep_blank_values)
256                 for pair in pairs:
257                     self.add_field(pair[0], pair[1])
258
(Pdb) parse_qsl("test_token=abcdefghij", 0)
[('test_token', 'abcdefghij')]
(Pdb) parse_qsl("Hakuna=Matata", 0)
[('Hakuna', 'Matata')]
(Pdb) parse_qsl("something_good=abcdefghij", 0)

Thread 3 "apache2" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe960d700 (LWP 58870)]
parse_qsl (self=<optimized out>, args=<optimized out>) at _apachemodule.c:380
380     _apachemodule.c: No such file or directory.

It seems like in src/_apachemodule.c
at line 376 and 377 we are decoding string to UTF8, if there is some error, it returns null which makes ukey or uval to be null and at line 379 and at line 380
we are running Py_DECREF which raises SIGSEGV segmentation fault when we pass null value in it