Using unstable version 2012-03-30.
Search followed by '.' doesn't always work the way it should. It will do a paste operation instead of the previously entered key sequence. Here's a scenario that creates two strings "somestring" using a paste operation, searches for the string, replaces the first 4 characters, repeats the search and then tries to use the period to repeat the replacement sequence.
Run the following commands in a new file:
Should result in <Newline>anewstring<Newline>anewstring<Newline>
The "n" takes you to the next search match. The "." should repeat the Ranew<Esc> sequence, but instead it repeats the last paste operation.
The issue isn't with the '.' paste operation, the issue is that 'R' is not modifying the 'last change' register. If you do "cwanew<Esc>" followed by 'n' and '.' it behaves as expected.
Thanks for the defect! I'll file this on our GitHub project.
I'm not sure how closely you're keeping an eye on things but I filed this defect based on your description: