Fix fold inconsistency #41
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This has a single transition, from LMT to GMT, in 1912.
Prior to this change, when a zone has a single transition (particularly to a zone with no DST), the fold handling logic in the C extension was broken, because the logic for detecting how to handle the first offset was incorrectly based on the number of transitions rather than the number of ttinfos. This bug was discovered by running the property tests over and over again hundreds of times; the minimal reproducing case has also been added to the unit tests.
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Prior to this change, when a zone has a single transition (particularly to a zone with no DST), the fold handling logic in the C extension was broken, because the logic for detecting how to handle the first offset was incorrectly based on the number of transitions rather than the number of ttinfos.
This bug was discovered by running the property tests over and over again hundreds of times; the minimal reproducing case has also been added to the unit tests.
@Zac-HD This is another one for the trophy case, if you're still collecting stuff caught prior to merge (though if I exposed the transitions for each zone, I think I could have found this by exhaustive testing, because there are only ~121k transitions across ~1800 time zones available on my machine).