Merge branch 'stable-4.9' into stable-4.10

* stable-4.9:
  Fix NoSuchFileException during directory cleanup in RefDirectory
  Externalize warning message in RefDirectory.delete()
  Suppress warning for trying to delete non-empty directory

Change-Id: Ied2d7a70c5544ff012687a1aeb6e07394d9bd6fd
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties

 tSizeMustBeGreaterOrEqual1=tSize must be >= 1
 unableToCheckConnectivity=Unable to check connectivity.
 unableToCreateNewObject=Unable to create new object: {0}
+unableToRemovePath=Unable to remove path ''{0}''
 unableToStore=Unable to store {0}.
 unableToWrite=Unable to write {0}
 unauthorized=Unauthorized

org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java

 	/***/ public String tSizeMustBeGreaterOrEqual1;
 	/***/ public String unableToCheckConnectivity;
 	/***/ public String unableToCreateNewObject;
+	/***/ public String unableToRemovePath;
 	/***/ public String unableToStore;
 	/***/ public String unableToWrite;
 	/***/ public String unauthorized;

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java

 		File dir = file.getParentFile();
 		for (int i = 0; i < depth; ++i) {
 			try {
-				Files.delete(dir.toPath());
+				Files.deleteIfExists(dir.toPath());
 			} catch (DirectoryNotEmptyException e) {
 				// Don't log; normal case when there are other refs with the
 				// same prefix
 				break;
 			} catch (IOException e) {
-				LOG.warn("Unable to remove path {}", dir, e);
+				LOG.warn(MessageFormat.format(JGitText.get().unableToRemovePath,
+						dir), e);
 				break;
 			}
 			dir = dir.getParentFile();