`_normalise_lines` drops blank lines and collapses whitespace WITHIN a line, so a reflow,
an indentation change, and a change to the spacing inside a STRING LITERAL are invisible.
The first two carry no meaning; the third could, and does not here. Line order and any
token change are caught. All four measured.
Stated because the phrase 'pinned whole' invites a reader to assume byte equality, and a
reader who assumes that will not check the one case where it matters.
Refs: #887
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019T79beF1Ufid3dXju4yqkF