Assign ticket to merged user fails

RT Users
1

We are using RT 4.4.1 with the RT::Extension::MergeUsers 1.0.2_01.
When trying to assign a ticket to a merged user i get the following error:

Deep recursion on subroutine "RT::User::CanonicalizeEmailAddress" at /opt/rt4/local/plugins/RT-Extension-MergeUsers/lib/RT/Extension/MergeUsers.pm line 199. (/opt/rt4/local/plugins/RT-Extension-MergeUsers/lib/RT/Extension/MergeUsers.pm:199)

Any idea how to solve this problem?

Thanks,
Jörg