Change:
- Make strategies behave consistently and return the empty string
instead of "UNKNOWN" (or "temporarystub") for the "before" value if
the permanent hostname file does not exist or could not be read.
- Switch to `with open()` instead of annoying exception handling code
(which was wrong and leaked file handles in several places). This
drops Python 2.4 support for this module.
- Updated porting guide since users could be relying on these former,
inconsistent values.
Signed-off-by: Rick Elrod <rick@elrod.me>
2ad10ffe43