+serve/... not supported in transclusions, almost supported in links

[RogerHaase]

Attempts to transclude a file in /wiki_local/ or /docs/ with a +serve/ prefix fails with the does not exist. Create it? dialog:

{{+serve/wiki_local/audio.mp3}}
{{+serve/docs/admin/configure.html?highlight=wiki_local}}

However, using the full url is acceptable:

{{http://127.0.0.1:5000/+serve/wiki_local/audio.mp3}}
{{http://127.0.0.1:5000/+serve/docs/admin/configure.html?highlight=wiki_local}}

When using +serve in a link, the text is gray, indicating non-existent, but the link works:

[[+serve/wiki_local/audio.mp3]]
[[+serve/docs/admin/configure.html?highlight=wiki_local]]

Using the full url produces a normal link in blue:

[[http://127.0.0.1:5000/+serve/wiki_local/audio.mp3]]
[[http://127.0.0.1:5000/+serve/docs/admin/configure.html?highlight=wiki_local]]