A 3.8.3 migration appended the section header with one backslash too many, so
sed wrote the literal characters instead of a newline plus the header. foot
rejects the line and stops reading the rest of the file. The later text-binding
migration matches the header with grep -qxF, misses the broken line, and appends
a second section, leaving the config broken across the Quattro upgrade.
Closes#6903
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
(cherry picked from commit b5bb8dac05)
