Fix invalid version check in setup.py.

IPython/__init__.py

@@ -24,6 +24,7 b' import sys'
 # Setup everything
 #-----------------------------------------------------------------------------
 
+# Don't forget to also update setup.py when this changes!
 if sys.version[0:3] < '2.6':
     raise ImportError('Python Version 2.6 or above is required for IPython.')
 

setup.py

@@ -21,14 +21,14 b' import sys'
 
 # This check is also made in IPython/__init__, don't forget to update both when
 # changing Python version requirements.
-if sys.version[0:3] < '2.5':
+if sys.version[0:3] < '2.6':
     error = """\
-ERROR: 'IPython requires Python Version 2.5 or above.'
+ERROR: 'IPython requires Python Version 2.6 or above.'
 Exiting."""
     print >> sys.stderr, error
     sys.exit(1)
 
-# At least we're on Python 2.5 or newer, move on.
+# At least we're on the python version we need, move on.
 
 #-------------------------------------------------------------------------------
 # Imports