Move the python version check into the python package

This ensures the check is run for anyone using the package, including
setup.py, though it's sad that it's necessary, since all it really wants is
__version__.

Ideally, we'd avoid the version check entirely in favor of checking for
functionality, but that's rather difficult with language constructs like
context managers, so this'll do for now.

(Bitbake rev: f936f1c0edf70860ea0f39ec1a500ba43b56f289)

Signed-off-by: Chris Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

bitbake/lib/bb/__init__.py

@@ -23,6 +23,10 @@
 
 __version__ = "1.11.0"
 
+import sys
+if sys.version_info < (2, 6, 0):
+    raise RuntimeError("Sorry, python 2.6.0 or later is required for this version of bitbake")
+
 import os
 import bb.msg