Timothy Luoma is trying to find this text:
| Content-Type: text/plain; charset="us-ascii"
with this condition:
| * ^Content-Type: text\/plain\; charset="us-ascii"
Escaping the semicolon, while unnecessary, is harmless, but escaping the
slash turns it into the extraction mark. You're now asking for
[newline]Content-Type: textplain; charset="us-ascii"
and trying to extract from "plain" onward. But that condition doesn't match
at all, because the actual text is "text/plain", not "textplain".
Don't escape the slash.