[Bug] [atree] Included file is showing errorneously up as nonexistent

[pbokoc]

Running atree on the RHEL8 docs repo, branch 8.0-GA, specifically on enterprise/titles/installing/performing-a-standard-rhel-installation/master.adoc, shows one of the included files as being nonexistent:

assemblies/assembly_installing-red-hat-enterprise-linux-on-ibm-power-system-l-server.adoc
     ...
     N! /modules/installer/con_powering-on-your-l-server-with-ipmi.adoc

The file exists, though:

$ file modules/installer/con_powering-on-your-l-server-with-ipmi.adoc
modules/installer/con_powering-on-your-l-server-with-ipmi.adoc: ASCII text

The problem is the include has a leading slash (include::/modules/installer/con_powering-on-your-l-server-with-ipmi.adoc[leveloffset=+1] in file enterprise/assemblies/assembly_installing-red-hat-enterprise-linux-on-ibm-power-system-l-server.adoc). None of the other includes in the title have a leading slash, this is likely to be the problem.

ASCIIDoctor/ccutil build the title fine.

[VladimirSlavik]

Apparently asciidoctor does something interesting to absolute paths. My guess is it reinterprets them to start at the starting file, or something along these lines. Needs more investigation.