odd cairo.Context error

Installed PyGObject and friends on OSX via homebrew, got the following strange error:

Traceback (most recent call last):
  File "/usr/local/Cellar/exaile/4.0.0rc2/lib/exaile/xlgui/widgets/playback.py", line 434, in do_draw
    Gtk.ProgressBar.do_draw(self, context)
TypeError: Expected cairo.Context

Source code snip:

class PlaybackProgressBar(Gtk.ProgressBar):
    ...

class _SeekInternalProgressBar(PlaybackProgressBar):
    ...

    def do_draw(self, context):
        Gtk.ProgressBar.do_draw(self, context)

When I print out the context, it says:

<cairo.Context object at 0x118229a78 (CairoContext at 0x7fcb4883d000)>

Versions:

• Python 2.7.15
• py2cairo 1.17.1
• pygobject 3.30.1
• OSX 10.12.6

If you want to duplicate it, you should be able to do brew install exaile/exaile/exaile and just run exaile, and the error will show up.

This is from a brand new homebrew install. Any thoughts on what might be going wrong? Not changing the context or anything, just passing it straight through.