LUCENE-2135: don't flush field cache if we hit exception during init (it leads to NPE)

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@890439 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/lucene/index/SegmentReader.java

@@ -106,7 +106,6 @@ public class SegmentReader extends IndexReader implements Cloneable {
       segment = si.name;
       this.readBufferSize = readBufferSize;
       this.dir = dir;
-      this.origInstance = origInstance;
 
       boolean success = false;
 
@@ -144,6 +143,12 @@ public class SegmentReader extends IndexReader implements Cloneable {
           decRef();
         }
       }
+
+      // Must assign this at the end -- if we hit an
+      // exception above core, we don't want to attempt to
+      // purge the FieldCache (will hit NPE because core is
+      // not assigned yet).
+      this.origInstance = origInstance;
     }
 
     synchronized TermVectorsReader getTermVectorsReaderOrig() {