Fix bug where 'if 1:' was being added to comment-only code....
Fix bug where 'if 1:' was being added to comment-only code.
Found by trying to paste and run this example:
http://matplotlib.sourceforge.net/examples/api/collections_demo.html
that happened to have indented, comment-only lines of the type:
code()
# comment
code()
In these cases, we should *not* try to prepend 'if 1:' to the user's
code since that comment by itself isn't executable, and it will cause
a compiler IndentationError.
