#16332: use "except OSError as e" in subprocess docs. Patch by Berker Peksag.

Doc/library/subprocess.rst

@@ -750,7 +750,7 @@ A more realistic example would look like this::
            print >>sys.stderr, "Child was terminated by signal", -retcode
        else:
            print >>sys.stderr, "Child returned", retcode
-   except OSError, e:
+   except OSError as e:
        print >>sys.stderr, "Execution failed:", e