java.lang.IllegalArgumentException because of bad chars

Despite clear written guidance, some user put characters like

/ \ :

in folder names. Unfortunately the RTC 3.0.1 Web Client accepts those.

This results in bad bavior with the Eclipse Client.
Is this a known RTC defect?
Any idea how to fix this before it's fixed in a future release?
I am thinking of a check-in rule that blocks bad characters.

Error
An internal error occurred during: "Loading repository items".
java.lang.IllegalArgumentException
at com.ibm.team.filesystem.client.internal.RelativeLocation.<init>(RelativeLocation.java:46)
at com.ibm.team.filesystem.client.internal.RelativeLocation.append(RelativeLocation.java:78)
at com.ibm.team.filesystem.client.internal.load.MergeLoadMutator.load(MergeLoadMutator.java:457)
at com.ibm.team.filesystem.client.internal.load.MergeLoadMutator.execute(MergeLoadMutator.java:285)
at com.ibm.team.filesystem.client.internal.operations.FileSystemOperation.run(FileSystemOperation.java:89)
at com.ibm.team.filesystem.client.internal.operations.LoadOperation.load(LoadOperation.java:972)
...