Switching CMake kits while CMake is running breaks original kit, can't run

Instructions:

• Rerun CMake in an initial build config (kit and build type).
• Switch to a different kit or build type before CMake finishes. Make sure your initial build config is not focused when CMake finishes processing it.

If you then switch back to your initial build config, Qt Creator thinks that CMake is still running, and does not allow you to run CMake, cancel CMake, or build the project. Generating a compilation database appears to work fine in this state, but I question whether the results are valid.

(Note that Qt Creator has no way to cancel an ongoing CMake run, even if you don't switch to a different build config. Is this a missing feature?)

Switching to other compilers or build types reruns CMake successfully and allows a build. Switching back to MinGW Debug causes the issue to appear again.

This seems similar to https://bugreports.qt.io/browse/QTCREATORBUG-19975, but this bug happens using file-api rather than CMake server.