Fix yet another sed bug. The s/// command would copy the \ of substitutions before deciding what to do with them (generally overwriting the \ with the new data). When the substitution was A) at the very end of the new string, B) resolved to nothing, it could leave a trailing \ that didn't belong there and didn't get overwritten because the "copy trailing data" part that copies the original string's null terminator already happened before the \ overwrote it. The ghostwheel() function restarts regexes after embedded NUL bytes, but if the string it's passed is _longer_ than the length it's told then it gets confused (and it means we're off the end of our allocation so segfaults are likely). Fix: test for \ first and move the "copy byte" logic into an else case.