parse_refspec.py: Refactor "if" statement

To have all cases clearly exclusive. Also, fix indentation.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ie94996c08df0b637c3a93ec28cb423b9dcb8e905
diff --git a/scripts/parse_refspec.py b/scripts/parse_refspec.py
index 83fd30e..77657d8 100755
--- a/scripts/parse_refspec.py
+++ b/scripts/parse_refspec.py
@@ -47,8 +47,7 @@
 
 if not changes:
     raise Exception("Can not find anything.")
-
-if len(changes) > 1:
-   print_topic_tip(changes)
+elif len(changes) > 1:
+    print_topic_tip(changes)
 else:
     print(changes[0]["currentPatchSet"]["ref"])