B03005 - Canceling monsters

Since monster cancellation sticks, it doesn't makes sense for Magicbane to
cancel a monster more than once.  Tweaked the messages to deal with this fact.
I decided to not make Magicbane's random effect "intelligent", which is what
changing it to use some other attack against a canceled monster would be.

doc/fixes34.2

@@ -76,6 +76,7 @@ choking while eating non-food always called the food "quick snack"
 short swords are not throwing weapons
 several sit-in-trap cases were unreachable
 curse candelabrum in bones, like other similar artifacts
+clear up Magicbane messages when it attempts to re-cancel a canceled monster
 
 
 Platform- and/or Interface-Specific Fixes

src/artifact.c

@@ -766,7 +766,8 @@ char *hittee;			/* target's name: "you" or mon_nam(mdef) */
     const char *verb;
     boolean youattack = (magr == &youmonst),
 	    youdefend = (mdef == &youmonst),
-	    resisted = FALSE, do_stun, do_confuse, result;
+	    resisted = FALSE, was_canceled = FALSE,
+	    do_stun, do_confuse, result;
     int attack_indx, scare_dieroll = MB_MAX_DIEROLL / 2;
 
     result = FALSE;		/* no message given yet */
@@ -809,6 +810,11 @@ char *hittee;			/* target's name: "you" or mon_nam(mdef) */
     verb = mb_verb[!!Hallucination][attack_indx];
     if (youattack || youdefend || vis) {
 	result = TRUE;
+	/* canceling monster only happens if not already canceled */
+	if (attack_indx == MB_INDEX_CANCEL && !youdefend && mdef->mcan) {
+	    was_canceled = TRUE;
+	    verb = "hit"; /* doesn't change its attack to, eg stun */
+	}
 	pline_The("magic-absorbing blade %s %s!",
 		  vtense((const char *)0, verb), hittee);
 	/* assume probing has some sort of noticeable feedback
@@ -821,7 +827,9 @@ char *hittee;			/* target's name: "you" or mon_nam(mdef) */
     switch (attack_indx) {
     case MB_INDEX_CANCEL:
 	old_uasmon = youmonst.data;
-	if (!cancel_monst(mdef, mb, youattack, FALSE, FALSE)) {
+	if (was_canceled) {
+	    /* nothing left to cancel */
+	} else if (!cancel_monst(mdef, mb, youattack, FALSE, FALSE)) {
 	    resisted = TRUE;
 	} else {
 	    do_stun = FALSE;