n pattern used to namespace <code class="docutils literal notranslate"><span class="pre">IMPORTED</span></code>
targets and <code class="docutils literal notranslate"><span class="pre">ALIAS</span></code> targets.  When computing the link dependencies of
a target, the name of each dependency could either be a target, or a file
on disk.  Previously, if a target was not found with a matching name, the name
was considered to refer to a file on disk.  This can lead to confusing error
messages if there is a typo