magic trap uncursing vs scroll of remove curse

Reported directly to devteam:  if a magic trap gave its uncurse
effect, scroll of remove curse could become discovered.

Turns out that it would happen if hero was wielding a stack of
unholy water potions.  It didn't matter whether they were known
as water or known to be cursed or whether hero was carrying any
scrolls of remove curse.

doc/fixes3-7-0.txt

@@ -1890,6 +1890,8 @@ for OPTIONS=symset:blank, S_engroom (engraving on a room floor spot) and
 setting perm_invent in RC file before setting windowtype (whether later in
 	that file or via NETHACKOPTIONS) could result in it staying False
 	depending upon whether the default windowtype supported it
+if hero was wielding potion(s) of unholy water and a magic trap gave its
+	remove curse effect, scroll of remove curse would become discovered
 
 
 Fixes to 3.7.0-x Platform and/or Interface Problems Exposed Via git Repository

src/trap.c

@@ -4236,9 +4236,11 @@ domagictrap(void)
             struct obj pseudo;
             long save_conf = HConfusion;
 
-            pseudo = cg.zeroobj; /* neither cursed nor blessed,
-                                    and zero out oextra */
-            pseudo.otyp = SCR_REMOVE_CURSE;
+            pseudo = cg.zeroobj; /* force 'uncursed' and zero out oextra */
+            /* used to be SCR_REMOVE_CURSE but that could cause seffects()
+               to have hero discover scroll of remove curse */
+            pseudo.otyp = SPE_REMOVE_CURSE;
+            pseudo.oclass = SPBOOK_CLASS;
             HConfusion = 0L;
             (void) seffects(&pseudo);
             HConfusion = save_conf;