When you merge a patch, especially a patch that has been waiting to be merged for more than 6 months, it is polite not to publicly mention that the patch required changes to the way it originally looked (a lot of patches do, especially when you didn’t provide much feedback during the 6 months waiting period), or that merging the patch required cleaning up, and introduced bugs.

Also, crediting the patch author in public communications doesn’t hurt.

If you fail to do that, people might feel that patches are not so welcome after all.