Fix an underflow resulting from the assumption !O_ISSET(sp, O_LEFTRIGHT) (ironically, the assumption is in a code block which is conditional on its converse).  This isn't strictly the correct fix; it's more of a workaround to prevent an infinite loop.  The correct fix (see ports/editors/nvi-devel/files/patch-vi-relative r1.1) would take a file off the vendor branch, but since the result for this version of nvi is identical, this route was elected.
Fix an underflow resulting from the assumption !O_ISSET(sp, O_LEFTRIGHT)
(ironically, the assumption is in a code block which is conditional on its
converse).  This isn't strictly the correct fix; it's more of a workaround
to prevent an infinite loop.  The correct fix (see
ports/editors/nvi-devel/files/patch-vi-relative r1.1) would take a file off
the vendor branch, but since the result for this version of nvi is
identical, this route was elected.

PR:		28687
Approved by:	-developers

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase