check-code: fix issues with finding patterns in unified tests, fix tests - old-style patterns without ^ were getting improperly anchored - finditer was matching against beginning of line poorly - \s was matching newlines - [^x] was matching newlines so we: - remove earlier hacks for multiline matching - fix unified test anchoring by adding .* - replace \s with [ \t] - replace [^x] with [^\nx] - force all matches into multiline mode so ^ anchors work This uncovers a number of test issues that are then repaired.