CRE-SEARCH? (defined in scsh/rx/re-low.scm) calls REGEXP-MATCH with
4th and 5th arguments indicating whether this corresponds to begin/end
of line. For matching a string, these must be #t. The reason it was
working previously (with both parameters set to #f) was a bug in
regexp1.c:116 (fixed now by placing the appropriate parenthesis),
caused by | having higher precedence than ?: in C (as a result, the
flags passed to the C regexp engine were not correctly computed).
jaortega