lib/matplotlib/tests/test_backends_interactive.py:117:Failed-----------------------------Capturedstderrcall-----------------------------FailedtoconnecttoMir:Failedtoconnecttoserversocket:NosuchfileordirectoryUnabletoinitserver:Couldnotconnect:ConnectionrefusedFailedtoconnecttoMir:Failedtoconnecttoserversocket:NosuchfileordirectoryUnabletoinitserver:Couldnotconnect:Connectionrefused(-c:14609):Gdk-CRITICAL**:gdk_cursor_new_for_display:assertion'GDK_IS_DISPLAY (display)'failedTraceback (mostrecentcalllast):File"/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_gtk3.py",line43,in<module>cursors.MOVE          :Gdk.Cursor.new(Gdk.CursorType.FLEUR),TypeError:constructorreturnedNULLDuringhandlingoftheaboveexception,anotherexceptionoccurred:Traceback (mostrecentcalllast):File"<string>",line7,in<module>File"/home/travis/build/matplotlib/matplotlib/lib/matplotlib/pyplot.py",line2341,in<module>switch_backend(rcParams["backend"])File"/home/travis/build/matplotlib/matplotlib/lib/matplotlib/pyplot.py",line207,inswitch_backendbackend_mod=importlib.import_module(backend_name)File"/home/travis/virtualenv/python3.6.7/lib/python3.6/importlib/__init__.py",line126,inimport_modulereturn_bootstrap._gcd_import(name[level:],package,level)File"/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_gtk3agg.py",line4,in<module>from .importbackend_agg,backend_cairo,backend_gtk3File"/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_gtk3.py",line52,in<module>raiseImportError(exc)ImportError:constructorreturnedNULL