* Thu Aug 20 14:56:44 1998

agrep -v fails to write anything unless at least one line (possibly, a
particular line) of the input matches the pattern that we're trying to
mismatch.  The non-glimpse agrep does not have this problem.  E.g.:

thalia[189]$ for p in O e n w o r ; do echo "Pattern '${p}':" ; echo "One@Two@Three" | tr '@' '\012'  | agrep -v ${p} ; done
Pattern 'O':
Pattern 'e':
Two
Pattern 'n':
Pattern 'w':
One
Pattern 'o':
One
Pattern 'r':
One
Two

thalia[190]$ for p in O e n w o r ; do echo "Pattern '${p}':" ; echo "One@Two@Three" | tr '@' '\012'  | agrep-2.04 -v ${p} ; done
Pattern 'O':
Two
Three
Pattern 'e':
Two
Pattern 'n':
Two
Three
Pattern 'w':
One
Three
Pattern 'o':
One
Three
Pattern 'r':
One
Two

The non-glimpse agrep uses bitap to do the search; the glimpse one uses bm.
Some pre-condition is unsatisfied in the call to bm, because it overruns the
input text buffer by a huge amount in attempting to find a pattern match.

It isn't obvious to me where this bug is arising, or how to fix it.
