Added \versionchanged comment to os.popen() noting that it was unreliable in earlier versions of Python; this is useful information for people interested in writing code that is portable across Python versions.
Added \versionchanged comment to os.popen() noting that it was unreliable
in earlier versions of Python; this is useful information for people
interested in writing code that is portable across Python versions.

Suggested by Peter Funk <pf@artcom-gmbh.de>.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator