Fix issue #4496: tslib.tz_convert(vals, tz1, tz2) may raise an IndexError exception.
Merge pull request #4497 from stenri/tslib_tz_convert_trans_pos_plus_1__bugfix

Fix issue #4496: tslib.tz_convert(vals, tz1, tz2) may raise an IndexErro...
BUG: GH4273, appending a 0-len table to HDFStore was raising