When a CVMFS-repo is already mounted at e.g. /mnt/a and one tries to mount it again at /mnt/b, the error message is:
The error message uses the string mountpoint which is the mountpoint of the new, attempted mount.
The actual old mountpoint is however queried in CheckConcurrentMount at
but the string mountpoint used there is a local variable, which is thrown away after querying it.