Link to external issue overwritten with link to nonexistent internal issue

[jabenninghoff]

In pkgdown 2.0.3, the following markdown links to #2092 in NEWS.md.

[#2092](https://github.com/r-lib/pkgdown/issues/2092)

In pkgdown 2.0.4, the same code links to the issue for the repository that generated the pkgdown, which seems to be caused by #2104, as a link is added within the link:

From https://github.com/jabenninghoff/testpkg/blob/9510b647385299efdd99d85125a32f6e11fb784c/docs/news/index.html#L54:

<li><p>See issue <a href="https://github.com/r-lib/pkgdown/issues/2092" class="external-link"></a><a href="https://github.com/jabenninghoff/testpkg/issues/2092" class="external-link">#2092</a></p></li>

Full reprex at: https://github.com/jabenninghoff/testpkg, see: NEWS.md, DESCRIPTION (URL, BugReports).

[hadley]

Hmmmm, this is going to be tricky to fix with our current regular expression based approach. Maybe we need to switch to something that uses more xpath.

[jabenninghoff]

One thought I had was, it should be possible to create a regex that matches most tags but not <a>, but XPath seems like a better approach.

[hadley]

Test for the problem:

  # or existing links
  expect_equal(repo_auto_link(pkg, "<a href=''>#123</a>"), "<a href=''>#123</a>")