Ignore non-inheritable revision ranges in svn:mergeinfo

Revision ranges can be non-inheritable, meaning, that the range on this path is not inherited by sub-paths without svn:mergeinfo set.

See:

https://subversion.apache.org/docs/api/1.12/svn__mergeinfo_8h.html#ad46a80dbdd6128bcf03ce27aa6cccf1f