Backport: Unicorns can have horns but not cast magic

src/main/java/com/minelittlepony/model/capabilities/IModelUnicorn.java

@@ -15,6 +15,11 @@ public interface IModelUnicorn extends IModel {
      */
     boolean canCast();
 
+    /**
+     * Returns true if this model has an visible horns.
+     */
+    boolean hasHorn();
+
     /**
      * Returns true if this model is currently using magic (horn is lit).
      * @return

src/main/java/com/minelittlepony/model/components/ModelPonyHead.java

@@ -61,7 +61,7 @@ public class ModelPonyHead extends ModelHumanoidHead implements ICapitated {
 
         super.render(entity, move, swing, ticks, headYaw, headPitch, scale);
 
-        if (metadata.hasMagic()) {
+        if (metadata.hasHorn()) {
             skeletonHead.postRender(scale);
             horn.renderPart(scale, entity.getUniqueID());
         }

src/main/java/com/minelittlepony/model/player/ModelUnicorn.java

@@ -116,6 +116,11 @@ public class ModelUnicorn extends ModelEarthPony implements IModelUnicorn {
         return metadata.hasMagic();
     }
 
+    @Override
+    public boolean hasHorn() {
+        return metadata.hasHorn();
+    }
+
     @Override
     public boolean isCasting() {
         return rightArmPose != ArmPose.EMPTY || leftArmPose != ArmPose.EMPTY;
@@ -137,9 +142,9 @@ public class ModelUnicorn extends ModelEarthPony implements IModelUnicorn {
     protected void renderHead(Entity entity, float move, float swing, float ticks, float headYaw, float headPitch, float scale) {
         super.renderHead(entity, move, swing, ticks, headYaw, headPitch, scale);
 
-        if (canCast()) {
+        if (hasHorn()) {
             horn.renderPart(scale, entity.getUniqueID());
-            if (isCasting()) {
+            if (canCast() && isCasting()) {
                 horn.renderMagic(getMagicColor(), scale);
             }
         }

src/main/java/com/minelittlepony/pony/data/IPonyData.java

@@ -35,6 +35,11 @@ public interface IPonyData extends IMetadataSection {
      */
     int getGlowColor();
 
+    /**
+     * Returns true if and only if this metadata represents a pony that has a horn.
+     */
+    boolean hasHorn();
+
     /**
      * Returns true if and only if this metadata represents a pony that can cast magic.
      */

src/main/java/com/minelittlepony/pony/data/PonyData.java

@@ -69,9 +69,14 @@ public class PonyData implements IPonyData {
         return glowColor;
     }
 
+    @Override
+    public boolean hasHorn() {
+        return getRace() != null && getRace().getEffectiveRace(false).hasHorn();
+    }
+
     @Override
     public boolean hasMagic() {
-        return getRace() != null && getRace().getEffectiveRace(false).hasHorn() && getGlowColor() != 0;
+        return hasHorn() && getGlowColor() != 0;
     }
 
     @Override