report a simple message when the historycache does not exist

Author: tulinkry

opengrok-indexer/src/main/java/org/opengrok/indexer/history/FileHistoryCache.java

@@ -35,6 +35,7 @@
 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.FileReader;
 import java.io.IOException;
@@ -789,6 +790,8 @@ public void clear(Repository repository) {
             // Remove all files which constitute the history cache.
             try {
                 IOUtils.removeRecursive(Paths.get(histDir));
+            } catch (FileNotFoundException ex) {
+                LOGGER.log(Level.WARNING, "directory {} does not exist", histDir);
             } catch (IOException ex) {
                 LOGGER.log(Level.SEVERE, "tried removeRecursive()", ex);
             }