naming wielded weapons

I'm surprised that no one has noticed this one yet.  When
wielding two weapons, naming either of them caused two-weapon
combat mode to stop (unless the weapon already had another name
which was long enough to be overwritten by the new name without
allocating a replacement object).

doc/fixes34.1

@@ -123,6 +123,7 @@ fix crash when using lookat on an known invisible monster with monster syms set
 prevent getting stuck in infinite loop when using wizard mode #levelchange
 	command to reduce level while having level-drain resistance
 naming an already wielded elven dagger "Sting" activates warning against orcs
+naming either of the wielded weapons unintentionally ends two-weapon combat
 
 
 Platform- and/or Interface-Specific Fixes

src/do_name.c

@@ -361,8 +361,12 @@ const char *name;
 	}
 
 	if (obj->owornmask) {
+		boolean save_twoweap = u.twoweap;
+		/* unwearing the old instance will clear dual-wield mode
+		   if this object is either of the two weapons */
 		setworn((struct obj *)0, obj->owornmask);
 		setworn(otmp, otmp->owornmask);
+		u.twoweap = save_twoweap;
 	}
 
 	/* replace obj with otmp */