As a maintainer, however, I'm far more lenient in these things. If someone takes the time to fix a bug or add a neat new feature in something I maintain, I'm greatful for it, and I'm not going to get anal about the pull request. If there's something about it I find needs changing, I'll accept the pull request and fix it myself (with a few exceptions), and inform the contributor of the changes I've made, why I made them.
I'd rather not make pull requests be an exercise in frustration for the contributor[1]. Usually, you want more people to help with your project, and frustrating your contributors isn't a good way to encourage that.
[1] I say this as someone who, with one pull request, spent several hours over a few days trying to get a 15-line change accepted (about 10 of which were comment lines), with lots of debate over the most of the requested changes being anal things like "add a space after the comma, remove a space after the =". I was damn near the end of my rope and ready to just say "fuck it, if you don't want my fix, don't take it, I'll just maintain my own fork."