linkrev: also adjust linkrev when bootstrapping 'follow' revset The follow revset (used by `hg log --follow`) now uses the new 'introrev' method to bootstrap its traversal. This catches issues from linkrev-shadowing of the changesets introducing the version of a file in source changeset. A new test has been added to display pathological cases. Another test is affected because it was meant to test this behavior but actually failed to do so for half of the output. The output are now similar.