The httpd24threading branch would not build using perl 5.20.0 built with -Duserelocatableinc.
When t/TEST started to run, it said it could not find the lib.pm module. It showed the @INC path, which contained the paths the mod_perl test had added, and the paths listed in the -Dotherlibdirs param used to build perl, but it did not show the main ones.
When I rebuilt perl without -Dotherlibdirs, Apache::Test started up fine. There was an error in a test that I will report separately.
I thought I needed -Duserelocatable that because of hamster maze symlinks in a legacy filesystem setup, where the same perl on NFS has a different absolute path on different servers where the volume is mounted on different paths, but then a consistent symlink is provided. Maybe I don't understand what the userelocatableinc option is for.