shrinking globs vs shop bill

A shop-owned glob picked up by the hero was added to shop's bill
and if that shrank to nothing it moved from the unpaid portion to
used-up portion as intended.  But once there it retained obj->owt
of 0 and if 'sanity_check' was enabled, that triggered a warning
every move until finally paid for.  Both the 'Ix' list of used-up
items and itemized shop billing revealed a weight of 0 aum if
'wizweight' was enabled.

Keep track of the weight a glob had when it becomes unpaid, then
reset from 0 to that amount if it becomes used-up.  This overloads
the obj->oextra->omid field which is an unsigned int previously
only used for corpses.  Now for globs it is pre-bill obj->owt which
is also unsigned int.  I didn't add new oextra access functions for
it; it is only used in two places and existing omid ones suffice.

doc/fixes37.0

@@ -900,6 +900,9 @@ misaligned potion colors due to lack of reset_glyphmap() following obj shuffle;
 closed doors were described as "horizontal closed door" or "vertical closed
 	door" instead of just "closed door"
 glob shrinkage while hero was away from glob's level wasn't handled properly
+unpaid shop-owned glob that shrank to nothing had weight 0 which triggered
+	onbill warnings when 'sanity_check' was On; for 'Ix' and itemized
+	billing, the empty weight was shown to player if 'wizweight' was On
 
 curses: 'msg_window' option wasn't functional for curses unless the binary
 	also included tty support

include/obj.h

@@ -23,7 +23,8 @@ struct oextra {
     char *oname;          /* ptr to name of object */
     struct monst *omonst; /* ptr to attached monst struct */
     char *omailcmd;       /* response_cmd for mail delivery */
-    unsigned omid;        /* for corpse; m_id of corpse's ghost */
+    unsigned omid;        /* for corpse: m_id of corpse's ghost; overloaded
+                           * for glob: owt at time added to shop's bill */
 };
 
 struct obj {

src/shk.c

@@ -946,6 +946,10 @@ obfree(register struct obj* obj, register struct obj* merge)
         if (!merge) {
             bp->useup = 1;
             obj->unpaid = 0; /* only for doinvbill */
+            /* for used up glob, put back origial weight in case it gets
+               formatted ('I x' or itemized billing) with 'wizweight' On */
+            if (obj->globby && !obj->owt && has_omid(obj))
+                obj->owt = OMID(obj);
             add_to_billobjs(obj);
             return;
         }
@@ -2483,9 +2487,14 @@ add_one_tobill(struct obj *obj, boolean dummy, struct monst *shkp)
     } else
         bp->useup = 0;
     bp->price = get_cost(obj, shkp);
-    if (obj->globby)
+    if (obj->globby) {
         /* for globs, the amt charged for quan 1 depends on owt */
         bp->price *= get_pricing_units(obj);
+        /* remember the weight this glob had when it was added to bill;
+           glob oextra_owt field overlays corpse omid field */
+        newomid(obj);
+        OMID(obj) = obj->owt;
+    }
     eshkp->billct++;
     obj->unpaid = 1;
 }