tzdata/zic/zdump time zone abbreviation warnings

As of tzdata-2016b, a new approach to providing tzdata time zone abbreviations has been implemented for new time zones. When new zones are created tzdata will now use numeric time zone abbreviations like "+03" rather than the earlier naming convention of inventing new abbreviations like "ASTT".

Additionally, as of tzdata-2017a there has been a policy of removal of zone abbreviations where these abbreviations have no official standing and were invented for convenience.

As a result of this change, some tzdata-2016b data entries may cause zic implementations derived from releases of tzdata-2005j through tzdata-2015e to issue warnings. The zdump command may also issue a warning for these new time zones.

For example, the new time zone Europe/Astrakhan was added in tzdata-2016b. Using the zdump program (which is part of the glibc package) with tzdata-2016b we see:

$ zdump -v Europe/Astrakhan | grep 2016
zdump: warning: zone "Europe/Astrakhan" abbreviation "+03" lacks alphabetic at start
Europe/Astrakhan  Sat Mar 26 22:59:59 2016 UT = Sun Mar 27 01:59:59 2016 +03 isdst=0 gmtoff=10800
Europe/Astrakhan  Sat Mar 26 23:00:00 2016 UT = Sun Mar 27 03:00:00 2016 +04 isdst=0 gmtoff=14400

The time zone information is correct. The warning is based on POSIX.1-1988. However, this restriction was removed in POSIX.1-2001. Therefore, the warning can be ignored.