Fix cow milking from cows from old saves with old milk not raw milk.

src/activity_handlers.cpp

@@ -1279,9 +1279,9 @@ void activity_handlers::milk_finish( player_activity *act, player *p )
         debugmsg( "could not find source creature for liquid transfer" );
         return;
     }
-    auto milked_item = source_mon->ammo.find( "milk_raw" );
+    auto milked_item = source_mon->ammo.find( source_mon->type->starting_ammo.begin()->first );
     if( milked_item == source_mon->ammo.end() ) {
-        debugmsg( "animal has no milk ammo type" );
+        debugmsg( "animal has no milkable ammo type" );
         return;
     }
     if( milked_item->second <= 0 ) {

src/game.cpp

@@ -4109,7 +4109,9 @@ void game::monmove()
 
         m.creature_in_field( critter );
         if( calendar::once_every( 1_days ) ) {
-            critter.refill_udders();
+            if( critter.has_flag( MF_MILKABLE ) ) {
+                critter.refill_udders();
+            }
             critter.try_biosignature();
             critter.try_reproduce();
         }

src/monexamine.cpp

@@ -668,14 +668,14 @@ void monexamine::tie_or_untie( monster &z )
 
 void monexamine::milk_source( monster &source_mon )
 {
-    const auto milked_item = source_mon.ammo.find( "milk_raw" );
-    if( milked_item == source_mon.ammo.end() ) {
-        debugmsg( "%s is milkable but has no milk in its starting ammo!",
-                  source_mon.get_name() );
+    std::string milked_item = source_mon.type->starting_ammo.begin()->first;
+    auto milkable_ammo = source_mon.ammo.find( milked_item );
+    if( milkable_ammo == source_mon.ammo.end() ) {
+        debugmsg( "The %s has no milkable %s.", source_mon.get_name(), milked_item );
         return;
     }
-    if( milked_item->second > 0 ) {
-        const int moves = to_moves<int>( time_duration::from_minutes( milked_item->second / 2 ) );
+    if( milkable_ammo->second > 0 ) {
+        const int moves = to_moves<int>( time_duration::from_minutes( milkable_ammo->second / 2 ) );
         g->u.assign_activity( ACT_MILK, moves, -1 );
         g->u.activity.coords.push_back( g->m.getabs( source_mon.pos() ) );
         // pin the cow in place if it isn't already

src/monster.cpp

@@ -362,22 +362,32 @@ void monster::try_reproduce()
 
 void monster::refill_udders()
 {
-    if( !has_flag( MF_MILKABLE ) ) {
+    if( type->starting_ammo.empty() ) {
+        debugmsg( "monster %s has no starting ammo to refill udders", get_name() );
         return;
     }
-    const auto milked_item = type->starting_ammo.find( "milk_raw" );
+    if( ammo.empty() ) {
+        // legacy animals got empty ammo map, fill them up now if needed.
+        ammo[type->starting_ammo.begin()->first] = type->starting_ammo.begin()->second;
+    }
     auto current_milk = ammo.find( "milk_raw" );
-    if( milked_item == type->starting_ammo.end() || current_milk == ammo.end() ) {
-        debugmsg( "%s is milkable but has no milk in its starting ammo!", get_name() );
-        return;
+    if( current_milk == ammo.end() ) {
+        current_milk = ammo.find( "milk" );
+        if( current_milk != ammo.end() ) {
+            // take this opportunity to update milk udders to raw_milk
+            ammo["milk_raw"] = current_milk->second;
+            // Erase old key-value from map
+            ammo.erase( current_milk );
+        }
     }
-    if( current_milk->second == milked_item->second ) {
+    // if we got here, we got milk.
+    if( current_milk->second == type->starting_ammo.begin()->second ) {
         // already full up
         return;
     }
     if( calendar::turn - udder_timer > 1_days ) {
         // no point granularizing this really, you milk once a day.
-        current_milk->second = milked_item->second;
+        ammo.begin()->second = type->starting_ammo.begin()->second;
         udder_timer = calendar::turn;
     }
 }
@@ -2816,7 +2826,9 @@ void monster::on_load()
     try_upgrade( false );
     try_reproduce();
     try_biosignature();
-    refill_udders();
+    if( has_flag( MF_MILKABLE ) ) {
+        refill_udders();
+    }
 
     const time_duration dt = calendar::turn - last_updated;
     last_updated = calendar::turn;

src/monstergenerator.cpp

@@ -1102,6 +1102,17 @@ void MonsterGenerator::check_monster_definitions() const
         if( mon.harvest == "null" && !mon.has_flag( MF_ELECTRONIC ) && mon.id != mtype_id( "mon_null" ) ) {
             debugmsg( "monster %s has no harvest entry", mon.id.c_str(), mon.harvest.c_str() );
         }
+        if( mon.has_flag( MF_MILKABLE ) && mon.starting_ammo.empty() ) {
+            debugmsg( "monster %s is flagged milkable, but has no starting ammo", mon.id.c_str() );
+        }
+        if( mon.has_flag( MF_MILKABLE ) && !mon.starting_ammo.empty() &&
+            !item( itype_id( mon.starting_ammo.begin()->first ) ).made_of( LIQUID ) ) {
+            debugmsg( "monster % is flagged milkable, but starting ammo %s is not a liquid type",
+                      mon.id.c_str(), mon.starting_ammo.begin()->first );
+        }
+        if( mon.has_flag( MF_MILKABLE ) && mon.starting_ammo.size() > 1 ) {
+            debugmsg( "monster % is flagged milkable, but has multiple starting_ammo defined", mon.id.c_str() );
+        }
         for( auto &spec : mon.species ) {
             if( !spec.is_valid() ) {
                 debugmsg( "monster %s has invalid species %s", mon.id.c_str(), spec.c_str() );

src/savegame_json.cpp

@@ -1935,6 +1935,14 @@ void monster::load( const JsonObject &data )
         normalize_ammo( data.get_int( "ammo" ) );
     } else {
         data.read( "ammo", ammo );
+        // legacy loading for milkable creatures, fix mismatch.
+        if( has_flag( MF_MILKABLE ) && !type->starting_ammo.empty() && !ammo.empty() &&
+            type->starting_ammo.begin()->first != ammo.begin()->first ) {
+            const std::string old_type = ammo.begin()->first;
+            const int old_value = ammo.begin()->second;
+            ammo[type->starting_ammo.begin()->first] = old_value;
+            ammo.erase( old_type );
+        }
     }
 
     faction = mfaction_str_id( data.get_string( "faction", "" ) );