Fixed SegmentTest test case time dependant occasional failures

As highlighted by latest automated Travis builds.

source/net/yacy/kelondro/rwi/IndexCell.java

@@ -153,6 +153,7 @@ public final class IndexCell<ReferenceType extends Reference> extends AbstractBu
                             // get a fresh ram cache
                             IndexCell.this.ram = new ReferenceContainerCache<ReferenceType>(IndexCell.this.factory, termOrder, termSize);
                         }
+                        // WARNING : if this cell is queried before this dump termination, terms are no longer in the cache and would therefore not be found
                         // dump the buffer
                         IndexCell.this.merger.dump(ramdump, dumpFile, IndexCell.this.array);
                         IndexCell.this.lastDump = System.currentTimeMillis();

test/java/net/yacy/search/index/SegmentTest.java

@@ -48,9 +48,13 @@ public class SegmentTest {
                 new File("test/DATA/INDEX/webportal/SEGMENTS"),
                 new File("test/DATA/INDEX/webportal/ARCHIVE"),
                 null, null);
+        
+        /* Warning : ensure the size is larger than the maximum number of test terms added to the index, otherwise
+         * query tests might randomly fail depending on when the index dump job (IndexCell.FlushThread) is run */
+        final int entityCacheMaxSize = 20;
 
         // connect RWI index
-        index.connectRWI(10, 1024);
+        index.connectRWI(entityCacheMaxSize, 1024);
     }
 
     @After