Operating system: UBUNTU 18.04.02 Linux-4.18.0-25-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 670MX/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 390.116
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-06-30 19:51, hash: rBbbb3500c9716
Also broke in the last build of 2.79
Short description of error
When you sculpt something with a very hard edge, like a Blob with a strong fallof, when undo there is broken geometry in all the contour were the blob was. It can be seen in the view-port and when you do again a Blob there is broken geometry in that places.
I can see the error also in wire-frame also. The only way to fix the issue is to go with Shift and pas on the surface, that restore the surface and the shading error in the view port, some brushes also fix the issue when you sculpt near this areas. Also cavity is able to see it in the viewport, that is why I think is a problem with the mesh data, and not the shading.
In 2.79 you have to enable smooth shading to see it, you can't see it with shading flat, but the error occurred when sculpting.
Exact steps for others to reproduce the error
Add a cube then a subdivision modifier with 6 subdivisión apply, go to sculpt mode, make a blob with the stroke in drag dot and an abrupt fallof.
Make a blob again in the same spot
Also present in 2.79: