Ignore <Project>_EXACT_VERSION when reconfiguring a project
In the case of a workspace like that from https://gitlab.cern.ch/lhcb/upgrade-hackathon-setup/ we may have one of the projects changing version after a git pull
and in that case the downstream projects get confused because they remember they were using a different version and will try to use that instead of the new one (with undefined behavior).
One possible solution is to ignore the <Project>_EXACT_VERSION
requirement if the project was already found.
/cc @sponce