Unable to run custom executable

On current git master branch of qtcreator (as of commit 62cafc1782369cde0605fbd6b1182a83d5473a12), it's no longer possible to run/debug a project that has a "Custom executable" set in the project's run settings if that executable was built by another build system.

When going to the project's run settings, you can see that there's a warning saying "The project no longer builds the target associated with this run configuration." and the rest is greyed out, s. attached screenshot.

The commit that introduced this behaviour is the following one:

commit 8536504caa216e599a6332261cd9fcafcbba296c
Author: hjk <hjk@qt.io>
Date:   Fri Feb 22 12:16:56 2019 +0100    ProjectExplorer: Upstream CMake's handling of outdated builds
    
    This is mainly there to make the local runconfiguration implementations
    more uniform. Both qmake and qbs will drop runconfigs for builds that
    are not available anymore, so that's a no-op for them.
    
    Change-Id: I8aa32d779f67cce7a4d4733cfbe0c9a136bfd3f7
    Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
 

It works again as desired when that commit is reverted.

IMHO this was a very useful feature (e.g. for projects like LibreOffice that use another build system to build the executable) and I'd be happy if it could be brought back.