Comment 1 for bug 1899611

Thanks for your report and for making Ubuntu better.

I can confirm this bug. The .in file was added as of:

apache2 (2.4.18-2ubuntu3.16) xenial; urgency=medium

  * On Linux, use pthread mutexes. On kfreebsd/hurd, continue using
    fctnl because they lack robust pthread mutexes.
    (LP: #1565744)

 -- Bryce Harrington <email address hidden> Thu, 16 Jul 2020 00:20:55 +0000

but you're correct in saying that the changelog entry does not mention the file. You are also correct in your guess: the file is a leftover of a search-and-replace operation; it should have probably been removed after the replace took place.

Even though the .in file is harmless (Apache will not try to load it in any way), it should not have been installed. I am marking this bug as Triaged and will contact Bryce to sync.

Thanks!