Make demon lords hostile if wielding Demonbane as well as Excalibur

This makes a lot of sense. Why would they hate one artifact sword so
much and not really care about the one that is especially designed to
kill their type personally?

doc/fixes37.0

@@ -112,6 +112,7 @@ potions of hallucination can give enlightenment
 add a small chance of surviving food poisoning
 deliberate level teleporter activation ignores magic resistance
 auto-id scroll of remove curse when a known buc-state was changed
+demon lords hate Demonbane
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository

src/makemon.c

@@ -1327,7 +1327,8 @@ int mmflags;
     if (is_dprince(ptr) && ptr->msound == MS_BRIBE) {
         mtmp->mpeaceful = mtmp->minvis = mtmp->perminvis = 1;
         mtmp->mavenge = 0;
-        if (uwep && uwep->oartifact == ART_EXCALIBUR)
+        if (uwep && (uwep->oartifact == ART_EXCALIBUR
+                     || uwep->oartifact == ART_DEMONBANE))
             mtmp->mpeaceful = mtmp->mtame = FALSE;
     }
     if (mndx == PM_LONG_WORM && (mtmp->wormno = get_wormno()) != 0) {

src/minion.c

@@ -230,7 +230,8 @@ register struct monst *mtmp;
 {
     long cash, demand, offer;
 
-    if (uwep && uwep->oartifact == ART_EXCALIBUR) {
+    if (uwep && (uwep->oartifact == ART_EXCALIBUR
+                 || uwep->oartifact == ART_DEMONBANE)) {
         pline("%s looks very angry.", Amonnam(mtmp));
         mtmp->mpeaceful = mtmp->mtame = 0;
         set_malign(mtmp);