Bug 2680: shapeshift spell cannot be cast twice.

Add a message and don't pay for the failed spell.

res/core/messages.xml

@@ -1299,6 +1299,14 @@
       <arg name="race" type="race"/>
     </type>
   </message>
+  <message name="sp_shapeshift_twice" section="errors">
+    <type>
+      <arg name="unit" type="unit"/>
+      <arg name="region" type="region"/>
+      <arg name="command" type="order"/>
+      <arg name="target" type="unit"/>
+    </type>
+  </message>
 
   <message name="sp_movecastle_fail_0" section="magic">
     <type>

res/translations/messages.de.po

@@ -1250,6 +1250,9 @@ msgstr "\"$unit($unit) verdient in $region($region) $int($amount) Silber durch U
 msgid "error180"
 msgstr "\"$unit($unit) in $region($region): '$order($command)' - Der Zauber schlägt fehl.\""
 
+msgid "sp_shapeshift_twice"
+msgstr "\"$unit($unit) in $region($region): '$order($command)' - $unit($target) ist bereits verzaubert.\""
+
 msgid "sp_shapeshift_fail"
 msgstr "\"$unit($unit) in $region($region): '$order($command)' - $unit($target) kann nicht $race($race,1) werden.\""
 

res/translations/messages.en.po

@@ -1253,6 +1253,9 @@ msgstr "\"$unit($unit) in $region($region): '$order($command)' - The spell fails
 msgid "sp_shapeshift_fail"
 msgstr "\"$unit($unit) in $region($region): '$order($command)' - $unit($target) cannot take the form of $race($race,1).\""
 
+msgid "sp_shapeshift_twice"
+msgstr "\"$unit($unit) in $region($region): '$order($command)' - $unit($target) is already under this spell.\""
+
 msgid "error290"
 msgstr "\"$unit($unit) in $region($region): '$order($command)' - Eine Einheit kann nur in einem Verband Mitglied sein.\""
 

src/spells.c

@@ -4512,13 +4512,16 @@ int sp_illusionary_shapeshift(castorder * co)
         return 0;
     }
     irace = u_irace(u);
-    if (irace == u_race(u)) {
-        trigger *trestore = trigger_changerace(u, NULL, irace);
-        add_trigger(&u->attribs, "timer", trigger_timeout((int)power + 3,
-            trestore));
-        u->irace = rc;
+    if (irace != u_race(u)) {
+        ADDMSG(&mage->faction->msgs, msg_feedback(mage, co->order,
+            "sp_shapeshift_twice", "target", u));
+        return 0;
     }
 
+    add_trigger(&u->attribs, "timer", trigger_timeout((int)power + 3,
+        trigger_changerace(u, NULL, irace)));
+    u->irace = rc;
+
     ADDMSG(&mage->faction->msgs, msg_message("shapeshift_effect",
         "mage target race", mage, u, rc));