auto-changelog includes tagged commits as changed

[xdumaine]

Here's an example showing the output Note the line - 2.0.1 under the v2.1.0 section. I think this is happening because some versions of npm don't include the v prefix in the tagged commit message. In this case, the v2.0.1 tag has a message of just 2.0.1 and so it's being picked up as a commit inside the next release.

#### [v2.1.0](https://github.com/[redacted]/[redacted]/compare/v2.0.1...v2.1.0)

> 27 October 2020

- [redacted] [`#5`](https://github.com/[redacted]/[redacted]/pull/5)
- 2.0.1 [`#156`](https://github.com/[redacted]/[redacted]/pull/156)

#### [v2.0.1](https://github.com/[redacted]/[redacted]/compare/v2.0.0...v2.0.1)

> 23 September 2020

- [redacted] [`#155`](https://github.com/[redacted]/[redacted]/pull/155)
- v2.0.0 [`#152`](https://github.com/[redacted]/[redacted]/pull/152)
- [redacted] [`[redacted]`](https://github.com/[redacted]/[redacted]/commit/[redacted])

I tried to fix this by using a custom ignore commit pattern, but it doesn't seem to work. I tried auto-changelog --ignore-commit-pattern v?\d+\.\d+\.\d+

[cookpete]

It looks like you are tagging commits but then merging them to the branch via pull request. The tagged commit will appear before the merge in the "timeline" so the merge falls into the next version, even though it is named after the older version. The only reason they are appearing in the changelog in the first place is because they are pull requests and not regular commits.

Once I've pushed the fix for #195 your use of --ignore-commit-pattern should work.