Packages with leading 'v' in package.json result in "Unrecognized patch file" error

I'm trying to create a patch for the [redlock](https://github.com/mike-marcacci/node-redlock) package, which specifies the version in it's package.json as `v5.0.0-beta.2`. The leading 'v' in that seems to break patch-package, causing it to output an error:

```
Unrecognized patch file in patches directory redlock+v5.0.0-beta.2.patch
```

I can work around this by manually renaming the generated patch file to remove the leading `v` from the version, which makes it work properly, but it would be nice if this manual step wasn't necessary.