[CMake] "the input line is too long" error after upgrading from 2.8.2 to 2.8.3

[Dieter Oberkofler]

I'm having a hard time to understand why after upgrading from CMake 2.8.2 to
2.8.3 I get "the input line is too long" when running nmake.
The problem must be related to the upgrade because moving back to 6.8.2 with
the absolute same build environment works like a charm.
The error message seems to generated by a rather long (about 500 characters)
command in a ADD_CUSTOM_COMMAND section.

Did someone else have this kind of problem?
Is it a known bug?
Any ideas on how to track this down or if there are any workarounds?

Thank you!