Ignore errors for sip with no setapi.

QuLogic · QuLogic · commit f3f85ed204de · 2021-04-28T02:40:52.000-04:00
Apparently, this happens (see #20040 and related issues) sporadically. We don't care if we can't change the sip API version (if it's already been set), so also stop caring if the `setapi` function doesn't exist. This should simply cause the Qt4 backend to fail correctly later with an `ImportError` instead, and thus fall back to the next backend candidate. Fixes #20040.
diff --git a/lib/matplotlib/backends/qt_compat.py b/lib/matplotlib/backends/qt_compat.py
@@ -117,7 +117,7 @@ def _setup_pyqt4_internal(api):
             for _sip_api in _sip_apis:
                 try:
                     sip.setapi(_sip_api, api)
-                except ValueError:
+                except (AttributeError, ValueError):
                     pass
         from PyQt4 import QtCore, QtGui
         import sip  # Always succeeds *after* importing PyQt4.
