prepare-ChangeLog and svn-create-patch don't show replaced files.
1. svn rm fileA
2. svn cp fileB fileA
You'll get no output for svn-create-patch in this situation, and prepare-ChangeLog will says "No changes found." If you do svn status you see "R + fileA".
NOTE: Attachment 14756 [details] on Bug 10342 fixes the prepare-ChangeLog part of this bug.
The svn-create-patch part still needs to be fixed, though.