Bug 417799

SUMMARY
I just got a wacom cintiq pro 24 and I discovered a couple of bugs with it but one of them soft locks krita.

STEPS TO REPRODUCE
1. select the brush tool, and you can paint some
2. flip you stylus and use the eraser (here you will notice the brush will swap instead of using the same brush but with eraser mode, behavior I don't like but ok)
3. flip your stylus again and use the brush but now it will not paint even though it changed the previous used brush.

OBSERVED RESULT
the switch between pen and eraser has an issue, when comming back again to paint after using the eraser.

EXPECTED RESULT
the pen tip should paint and the eraser tip should erase.

SOFTWARE/OS VERSIONS
Windows: 10
Qt Version: 5

ADDITIONAL INFORMATION
the work around to use the pen again is to change the brush and then reselect the previous brush. flipping between tools does not work.

I have been working on a small python tool that is nothing special but I have noticed other odd behaviours too like PyQt5 not detecting which end of the stylus it is being used or it not knowing what kind of stylus it is, or if it is approaching or leaving. thought I would mention it while I am here.