The new package transformation option --without-tests works by setting
#:tests? #f in the specified packages.  But some packages replace
their 'check phase and no longer honor #tests?.  glib for example.

Attached is an attempt to document this current behavior.  Shall I
push it?  Alternatively, it should be documented to write a check
phase that honors #:tests?.  Or the package transformation should be
changed to remove any check phase it finds.

Regards,
Florian