From 531b64429738b28920669157970084bcd1a2a2e5 2011-04-10 10:41:04
From: Thomas Kluyver <takowl@gmail.com>
Date: 2011-04-10 10:41:04
Subject: [PATCH] Don't increment execution_count on empty cells. +test.

---

diff --git a/IPython/core/interactiveshell.py b/IPython/core/interactiveshell.py
index 5af556b..f308f8c 100644
--- a/IPython/core/interactiveshell.py
+++ b/IPython/core/interactiveshell.py
@@ -2118,6 +2118,9 @@ class InteractiveShell(Configurable, Magic):
           history. For user code calling back into IPython's machinery, this
           should be set to False.
         """
+        if not cell.strip():
+            return
+        
         raw_cell = cell
         with self.builtin_trap:
             cell = self.prefilter_manager.prefilter_lines(cell)
diff --git a/IPython/core/tests/test_interactiveshell.py b/IPython/core/tests/test_interactiveshell.py
index 2a3b95c..6c8fb79 100644
--- a/IPython/core/tests/test_interactiveshell.py
+++ b/IPython/core/tests/test_interactiveshell.py
@@ -41,7 +41,9 @@ class InteractiveShellTestCase(unittest.TestCase):
         """Just make sure we don't get a horrible error with a blank
         cell of input. Yes, I did overlook that."""
         ip = get_ipython()
+        old_xc = ip.execution_count
         ip.run_cell('')
+        self.assertEquals(ip.execution_count, old_xc)
 
     def test_run_cell_multiline(self):
         """Multi-block, multi-line cells must execute correctly.