bug#33552: Possible bug with handling -I option

[Paul Eggert]

Jason, thanks for reporting this grep bug <https://bugs.gnu.org/33552>. It
strikes me that this is related to another grep bug <https://bugs.gnu.org/29668>
concerning the "Binary files ..." message. Although they're not the same bug,
it's likely that fixing one will also entail fixing the other. So I'll add a
message to both bug reports to this effect.