Tyra crashed suddenly and a restart causes this error

```
python3 run_webapp.py
Failed to import the site module
Traceback (most recent call last):
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/site.py", line 703, in
main()
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/site.py", line 683, in main
paths_in_sys = addsitepackages(paths_in_sys)
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/site.py", line 282, in addsitepackages
addsitedir(sitedir, known_paths)
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/site.py", line 204, in addsitedir
addpackage(sitedir, name, known_paths)
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/site.py", line 173, in addpackage
exec(line)
File "", line 1, in
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/types.py", line 166, in
import functools as _functools
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/functools.py", line 23, in
from weakref import WeakKeyDictionary
File "/mnt/data/public_safety/charlotte_eis/tyra_cmpd_dump/tyra_venv/lib/python3.5/weakref.py", line 12, in
from _weakref import (
ImportError: cannot import name '_remove_dead_weakref'
```