As noted in bug 241925, compat-wxGTK26 is calling g_thread_init after other glib functions have been called. There's a patch in that bug to fix this issue. I suspect that this may apply to current wxGTK as well, although I haven't checked. I'm filing this under gtk2 because there are neither wxGTK nor compat-wxGTK26 components in bugzilla.
Yes, wxGTK 2.8 is also affected.
There's a bunch of similar bugs -- apparently the root problem is in glib2 itself. Therefore, these probably should all be closed as duplicates of bug #241925.