Portfile magic / xinstall usage / defect?

[Joshua Root]

> The brotli Portfile:https://github.com/macports/macports-ports/blob/master/archivers/brotli/Portfile
> Contains:
>    post-destroot {
>       xinstall -m 640 {*}[glob ${worksrcpath}/docs/*.1] ${destroot}${prefix}/share/man/man1/
> …
>    }
>
> However, after port installation, I look in the work directory and see:
>    ls -la destroot/opt/local/share/man/man1
>       -r--r--r--  root  admin  …  brotli.1.gz
>
> Also, /opt/local/share/man/man1/brotli.1.gz contains the same perms and .ext (as the above work/destroot).
>
> * How is the permissions mode 444, instead of 640 (as designated in the post-destroot block)?
> * And how did it get the .gz extension?

If you look in the log file for the brotli build after running e.g. 
'sudo port destroot brotli', you'll see a line saying "Compressing man 
pages for brotli". That comes from this code (which runs after all 
Portfile-defined destroot code): 
<https://github.com/macports/macports-base/blob/v2.8.1/src/port1.0/portdestroot.tcl#L201>

- Josh