A job is configured with Git SCM, and either "clean after checkout" or "wipe out workspace before build" option is enabled.
If the workspace contains a 'directory junction' (Windows slave) then, the "clean"/"wipeout" will follow the symlink (junction), and will delete files in the directory referenced by this symlink, and not just the symlink.
This is a problem since other jobs are using these files...
NOTE: it only affects Windows slaves; when a similar job is run on a Linux slave, it does not follow symlinks.