Remove whitespace after -I, this will cause diff to parse the whitespace as the parameter instead of the actual regexp.
spotted by thesteo82

Merge revision 1102932 by je4d from 3_way_kompare.

(This has been sitting in the branch for 7 months! Next time, if you fix something in a work branch, please also commit the fix to the trunk and the current release branch. Thanks in advance.)