make pdfdocs errors with 4.10-rc8

From: Jim Davis
Date: Tue Feb 14 2017 - 14:14:14 EST

On a Fedora 25 system,

build succeeded, 32 warnings.
make PDFLATEX=xelatex LATEXOPTS="-interaction=batchmode" -C
xelatex -interaction=batchmode 'linux-user.tex'
This is XeTeX, Version 3.14159265-2.6-0.99996 (TeX Live 2016)
(preloaded format=xelatex)
restricted \write18 enabled.
entering extended mode
Makefile:66: recipe for target 'linux-user.pdf' failed
Documentation/Makefile.sphinx:83: recipe for target 'pdfdocs' failed
Makefile:1450: recipe for target 'pdfdocs' failed

where Documentation/output/latex/linux-user.log contains

[jim@krebstar latex]$ grep '^!' linux-user.log | sort -u
! Extra }, or forgotten \endgroup.
! Missing } inserted.

and that happens often enough that Tex bails:

[jim@krebstar latex]$ tail -20 linux-user.log
! Extra }, or forgotten \endgroup.
<inserted text> }

l.14911 \hline\end{tabulary}

(That makes 100 errors; please try again.)