Add an ALWAYS on an unreachable branch in the ALTER TABLE logic.

FossilOrigin-Name: ebcd4523171f0988ff08e2bf36fb8a0caa40efe7ac7556b4eb206784969b03e4

manifest

@@ -1,5 +1,5 @@
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-D 2018-10-03T11:13:30.633
+C Add\san\sALWAYS\son\san\sunreachable\sbranch\sin\sthe\sALTER\sTABLE\slogic.
+D 2018-10-03T18:05:36.483
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-F src/alter.c b929e4daabe215300aa9b4e353977714c1751d91aaa63e52f0a475b840ce245e
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manifest.uuid

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src/alter.c

@@ -1061,7 +1061,9 @@ static int renameResolveTrigger(Parse *pParse, const char *zDb){
       db->aDb[sqlite3SchemaToIndex(db, pNew->pTabSchema)].zDbSName
   );
   pParse->eTriggerOp = pNew->op;
-  if( pParse->pTriggerTab ){
+  /* ALWAYS() because if the table of the trigger does not exist, the
+  ** error would have been hit before this point */
+  if( ALWAYS(pParse->pTriggerTab) ){
     rc = sqlite3ViewGetColumnNames(pParse, pParse->pTriggerTab);
   }