Guake fails to load with error "ImportError: /usr/lib/libharfbuzz.so.0: undefined symbol: FT_Get_Var_Blend_Coordinates"

### Environment details
Guake version: 0.8.8-1
Arch Linux: kernel 4.8.16.r201701062021-1-grsec
Gnome: 3.22.2 (using X instead of Wayland)

### Issue
When I try to launch guake from the terminal I get the following error:
```
Traceback (most recent call last):
File "/usr/lib/python2.7/runpy.py", line 174, in _run_module_as_main
"__main__", fname, loader, pkg_name)
File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
exec code in run_globals
File "/usr/lib/python2.7/site-packages/guake/main.py", line 28, in
import gtk
File "/usr/lib/python2.7/site-packages/gtk-2.0/gtk/__init__.py", line 40, in
from gtk import _gtk
ImportError: /usr/lib/libharfbuzz.so.0: undefined symbol: FT_Get_Var_Blend_Coordinates
```

Please let me know what other information I can provide to help track down the issue.

Thanks!