Gentoo's Bugzilla –
Attachment 599566 Details for
Bug 702976dev-python/PyQt5-5.13.2 : FileNotFoundError: [Errno 2] No such file or directory: '/tmp/portage/dev-python/PyQt5-5.13.2/image/PyQt5_tmp_root/usr/lib64/python3.6/site-packages/PyQt5/QtWebKitWidgets.pyi'