[orca] Eliminate false positive in isClipboardTextChangedEvent()

[Joanmarie Diggs <joanied src gnome org>]

commit 77e4c4ea55f8b1f05f955e939b7d752737db64c3
Author: Joanmarie Diggs <jdiggs igalia com>
Date:   Fri Feb 19 11:23:28 2016 -0500

    Eliminate false positive in isClipboardTextChangedEvent()

 src/orca/script_utilities.py |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/orca/script_utilities.py b/src/orca/script_utilities.py
index b3b17ad..24d52d2 100644
--- a/src/orca/script_utilities.py
+++ b/src/orca/script_utilities.py
@@ -3950,6 +3950,8 @@ class Utilities:
                 return False
 
         contents = self.getClipboardContents()
+        if not contents:
+            return False
         if event.any_data == contents:
             return True