LocalDiskRepositoryManager: Handle failure to visit file/path

If Files.walkFileTree fails due to a directory or file in the git root
being inaccessible, it throws an exception and subsequent directories
are not processed.

Override the visitFileFailed method on the visitor. Log the error and
continue.

Bug: Issue 5698
Change-Id: I7f4d76b30f3f8907128dacf357b70eea47fb0962

gerrit-server/src/main/java/com/google/gerrit/server/git/LocalDiskRepositoryManager.java

@@ -405,6 +405,12 @@ public class LocalDiskRepositoryManager implements GitRepositoryManager,
       return FileVisitResult.CONTINUE;
     }
 
+    @Override
+    public FileVisitResult visitFileFailed(Path file, IOException e) {
+      log.warn(e.getMessage());
+      return FileVisitResult.CONTINUE;
+    }
+
     private boolean isRepo(Path p) {
       String name = p.getFileName().toString();
       return !name.equals(Constants.DOT_GIT)