System Information
Operating system: Linux-4.15.0-62-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.116

Blender Version
Broken: version: 2.81 (sub 14), branch: master, commit date: 2019-10-10 23:31, hash: rBf9cc51788bd6
Broken: version: 2.81 (sub 15), branch: master, commit date: 2019-10-12 15:33, hash: rB95f020c853d6
Worked: version: 2.81 (sub 14), branch: master, commit date: 2019-10-06 14:05, hash: rB54a9649e2636

Short description of error
Left - broken, right - works:

Doesn't work correctly in compositing nodes also.

Exact steps for others to reproduce the error
Add mask in image editor.
Check it using Mask Display ->overlay