I was using tip of master (Slicer_VERSION 4.11.0), but the version of the internal Slicer-build was set to 4.9 from an old build.
The result is that I have two folders after the build: Slicer-build/lib/Slicer-4.11 and Slicer-build/lib/Slicer-4.9

Removing the cache in Slicer-build/CMakeCache.txt solves the problem, but clearing caches should not be needed.

I guess a possible solution would be to pass the version computed in the top CMakeListst.txt to the "external project" Slicer.

Here: https://github.com/Slicer/Slicer/blob/master/SuperBuild.cmake#L523-L552

I was having tip of master (Slicer_VERSION 4.11.0), but the version of Slicer-build was set to 4.9 from an old build.

Removing the cache in Slicer-build/CMakeCache.txt solves the problem, but clearing caches should not be needed.

I guess a possible solution would be to pass the version computed in the top CMakeListst.txt to the "external project" Slicer.

Here: https://github.com/Slicer/Slicer/blob/master/SuperBuild.cmake#L523-L552

The result of this is that I would have two folders: Slicer-build/lib/Slicer-4.11 and Slicer-build/lib/Slicer-4.9

I was having tip of master (Slicer_VERSION 4.11.0), but the version of Slicer-build was set to 4.9 from an old build.

Removing the cache in Slicer-build/CMakeCache.txt solves the problem, but clearing caches should not be needed.

I guess a possible solution would be to pass the version computed in the top CMakeListst.txt to the "external project" Slicer.

Here: https://github.com/Slicer/Slicer/blob/master/SuperBuild.cmake#L523-L552