A block scalar is indented with spaces only, so a tab past the content
indentation is literal content. The indentation scan measured the leading
whitespace as a tab-expanded width and rebuilt the surplus beyond the
indentation as spaces, so a line like `␣\ttext` under a one-space indent came
out ` text` rather than `\ttext`: the tab became three spaces.
Record the literal leading-whitespace characters during the indentation scan
and reconstruct the surplus from them, walking columns the way the width scan
does and keeping the remainder verbatim. A tab stays a tab; surplus spaces
stay spaces; the blank-line surplus path uses the same reconstruction.
Raises yaml-test-suite value-level conformance to 180/194 (92.8%) with the
parse-level and should-error rejection rates unchanged. 438 tests pass.
Mihaela M
4b0dc9375e