babel 3.25: xelatex fails when \babelprovide is used

[u-fischer]

\RequirePackage{latexbug}
\documentclass{article}
\usepackage[main=english]{babel}
\babelprovide[import]{german}

\begin{document}
abc
\end{document}

fails when compiled with xelatex
with

? 
! Missing \endcsname inserted.
<to be read again> 
                   \bbl@sbcp@english 

Imho the problem is in the new xelatex related code around line 1410 in babel.def

Log file (required) and possibly PDF file

test-utf8.log

(the bblopts.cfg mentioned in the log is an empty file, that I need to keep miktex for looking for it ...).

With babel 3.24 the file compiles fine.

[jbezos]

Fixed and pushed (but a better fix is necessary).