Demons cannot be frightened by showing them their reflection

From xnethack by copperwater <aosdict@gmail.com>.

doc/fixes3-7-0.txt

@@ -1328,6 +1328,7 @@ avoid impossible "trapped without a trap (fmon)" from 'sanity_check' when a
 	caused adjacent pool/moat/lava to flood that spot; if a non-floater,
 	non-flyer monster survived that it got marked as trapped even though
 	flooding deleted the trap
+demons cannot be frightened by showing them their reflection
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

src/apply.c

@@ -1144,6 +1144,7 @@ use_mirror(struct obj *obj)
         if (!tele_restrict(mtmp))
             (void) rloc(mtmp, RLOC_MSG);
     } else if (!is_unicorn(mtmp->data) && !humanoid(mtmp->data)
+               && !is_demon(mtmp->data)
                && (!mtmp->minvis || perceives(mtmp->data)) && rn2(5)) {
         boolean do_react = TRUE;