lintian: E: xen source: license-problem-gfdl-invariants

When running lintian on xen_4.11.0-1~_amd64.changes:

E: xen source: license-problem-gfdl-invariants stubdom/grub.patches/00cvs invariant part is: with no invariant sections, with the front-cover texts being a gnu manual, and with the back-cover texts as in (a) below
N: 
N:    The given source file is licensed under GFDL with invariant section or
N:    front-cover or back-cover text.
N:    
N:    GFDL with invariant sections, front-cover or back-cover texts are not
N:    suitable for main.
N:    
N:    Should this file be multi-licensed, please override the tag.
N:    
N:    Should this be a false-positive, please report a bug.
N:    
N:    Refer to https://wiki.debian.org/qa.debian.org/gfdlinvariant and
N:    https://www.debian.org/vote/2006/vote_001 for details.
N:    
N:    Severity: serious, Certainty: possible
N:    
N:    Check: cruft, Type: source
N: