The #2799 fallback (utf-8 -> host codepage -> latin-1) turned a BOM'd UTF-16
ignore file (what PowerShell Set-Content / Notepad 'Unicode' write) into
NUL-laden mojibake via latin-1, so its rules matched nothing. Detect the
UTF-16 BOM and decode as utf-16 before the latin-1 fallback. Adds an
end-to-end UTF-16 exclusion test and a direct no-NUL-garbage test.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Ignore files were read with errors="ignore", so a mis-encoded byte in a rule
(e.g. a cp1252 accented directory name) was deleted, turning the pattern into
one that matches nothing — an exclusion that silently failed open. Both
rule-read sites now decode UTF-8-BOM first, then fall back to the host codepage
and latin-1 (never raising, never dropping bytes), with a one-time warning; the
rule survives intact instead of being truncated.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
