network blip can cause offlineimp to hang

[Rafael Ávila de Espíndola]

I had a network blip while syncing my account. I tried Control-C, and
offlineimap printed:

Terminating NOW (this may take a few seconds)...

But never finished. Running strace shows

....
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
select(0, NULL, NULL, NULL, {0, 50000}) = 0 (Timeout)
....

gdb shows

#0  0x0000003717ee8933 in select () from /lib64/libc.so.6
#1  0x00007f93b8a21e9d in ?? ()
   from /usr/lib64/python2.7/lib-dynload/timemodule.so
#2  0x000000371eadffbb in PyEval_EvalFrameEx ()
...

Not sure how to print a python backtrace from it...

Cheers,
Rafael