After taking a look at http://code.metager.de/source/xref/gnu/glibc/timezone/africa I'm thinking that maybe parse_tzfile should be returning WAT instead of AOT.

```
105# Angola
106# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
107Zone	Africa/Luanda	0:52:56	-	LMT	1892
108			0:52:04	-	AOT	1911 May 26 # Angola Time
109			1:00	-	WAT
```