Segfault in uuid.py calling _uuid_generate_time after importing pandas
I am seeing a new but consistently repeatable segmentation fault in our application test suite, running CPython 2.7.8, when calling `_uuid_generate_time(_buffer)` from uuid.py (somewhere inside the kombu library).

The salient difference that makes this segfault occur is if I import pandas before the test run. If I don't, all is well. If I import pandas (and do nothing else differently), the segfault occurs later on (after the pandas import completes without problems), when I call `.apply_async()` on a task in celery, leading kombu to generate a UUID.

This seems to be a matter of the pandas import leaving libuuid1 in some broken state. In particular, it's _not_ a matter of multiple concurrent threads at the time of the segfault; there is only ever one thread, as confirmed by tracing via `threading.settrace` (no output) and by inspecting the core in gdb:

```
$ gdb /var/pythonenv/JENKINSBUILD/bin/python ../test/core 
GNU gdb (GDB) 7.4.1-debian
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /var/pythonenv/JENKINSBUILD/bin/python...done.

warning: core file may not match specified executable file.
[New LWP 19262]

warning: Can't read pathname for load map: Input/output error.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/i686/cmov/libthread_db.so.1".
Core was generated by `/var/pythonenv/JENKINSBUILD/bin/python /var/pythonenv/JENKINSBUILD/bin/unit2 di'.
Program terminated with signal 11, Segmentation fault.
#0  0xb75da5ad in rewind () from /lib/i386-linux-gnu/i686/cmov/libc.so.6
(gdb) info threads
  Id   Target Id         Frame 
* 1    Thread 0xb75748d0 (LWP 19262) 0xb75da5ad in rewind () from /lib/i386-linux-gnu/i686/cmov/libc.so.6
(gdb) bt
#0  0xb75da5ad in rewind () from /lib/i386-linux-gnu/i686/cmov/libc.so.6
#1  0xb6872dcf in __uuid_generate_time () from /lib/i386-linux-gnu/libuuid.so.1
#2  0xb6873417 in ?? () from /lib/i386-linux-gnu/libuuid.so.1
#3  0xb688e622 in ffi_call_SYSV () at /usr/local/pythonz/build/CPython-2.7.8/Modules/_ctypes/libffi/src/x86/sysv.S:65
#4  0xb688e3eb in ffi_call (cif=cif@entry=0xbfa6c9e8, fn=fn@entry=0xb68734c0 <uuid_generate_time>, rvalue=rvalue@entry=0xbfa6c950, avalue=avalue@entry=0xbfa6c930)
    at /usr/local/pythonz/build/CPython-2.7.8/Modules/_ctypes/libffi/src/x86/ffi.c:411
#5  0xb6886baa in _call_function_pointer (argcount=1, resmem=0xbfa6c950, restype=0x0, atypes=0x87bd050, avalues=0xbfa6c930, pProc=0xb68734c0 <uuid_generate_time>, flags=4353)
    at /usr/local/pythonz/build/CPython-2.7.8/Modules/_ctypes/callproc.c:836
#6  _ctypes_callproc (pProc=pProc@entry=0xb68734c0 <uuid_generate_time>, argtuple=argtuple@entry=0xb2fbc2ac, flags=4353, argtypes=argtypes@entry=0x0, restype=restype@entry=0xb69533dc, checker=checker@entry=0x0)
    at /usr/local/pythonz/build/CPython-2.7.8/Modules/_ctypes/callproc.c:1183
#7  0xb687df4b in PyCFuncPtr_call (self=0xb6941234, inargs=0xb2fbc2ac, kwds=0x0) at /usr/local/pythonz/build/CPython-2.7.8/Modules/_ctypes/_ctypes.c:3965
#8  0x080660f3 in PyObject_Call (func=func@entry=0xb6941234, arg=arg@entry=0xb2fbc2ac, kw=kw@entry=0x0) at Objects/abstract.c:2529
#9  0x080e2517 in do_call (nk=<optimized out>, na=<optimized out>, pp_stack=0xbfa6cbc4, func=0xb6941234) at Python/ceval.c:4251
#10 call_function (oparg=<optimized out>, pp_stack=0xbfa6cbc4) at Python/ceval.c:4056
#11 PyEval_EvalFrameEx (f=f@entry=0xb2f5983c, throwflag=throwflag@entry=0) at Python/ceval.c:2679
```

With `sys.settrace` I've narrowed the fault down to this `_uuid_generate_time` call, the last trace events being:

```
call, /var/pythonenv/JENKINSBUILD/lib/python2.7/site-packages/celery/app/base.py:615
line, /var/pythonenv/JENKINSBUILD/lib/python2.7/site-packages/celery/app/base.py:617
call, /var/pythonenv/JENKINSBUILD/lib/python2.7/site-packages/kombu/common.py:61
line, /var/pythonenv/JENKINSBUILD/lib/python2.7/site-packages/kombu/common.py:62
call, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:476
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:486
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:489
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:490
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:493
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:495
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:496
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:497
call, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:457
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:459
call, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/ctypes/__init__.py:52
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/ctypes/__init__.py:57
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/ctypes/__init__.py:64
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/ctypes/__init__.py:65
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/ctypes/__init__.py:66
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/ctypes/__init__.py:67
return, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/ctypes/__init__.py:67
line, /usr/local/pythonz/pythons/CPython-2.7.8/lib/python2.7/uuid.py:460
```

and then the segfault.

This is a CPython 2.7.8 built locally using [pythonz](https://github.com/saghul/pythonz) on Debian Wheezy, and with pandas 0.15.0 installed, inside a virtualenv. Some relevant system package version info:

```
libc-bin 2.13-38+deb7u6
libc-dev-bin 2.13-38+deb7u6
libc6:i386 2.13-38+deb7u6
libc6-dev:i386 2.13-38+deb7u6
libc6-i686:i386 2.13-38+deb7u6
libuuid1:i386 2.20.1-5.3
```

Anything else I can provide that's useful?
