Issue Summary

On certain user default settings, the GMT timezone is not handled properly by the CSV importer

Steps to Reproduce

1. Go to Jira Settings > System > General Configuration
2. Set the Default user time zone to America/Los Angeles
3. Import a date time custom field value via CSV.

Value : 11-04-18 09:01 GMT
Importer Date Format : MM-dd-yy HH:mm z

Expected Results

The time stored on the database should be 09:01 GMT and will be displayed according to the end user's timezone settings.

Actual Results

The time stored in the database is an hour behind (ie. 08:01 GMT). The incorrect time is displayed according to the end user's timezone settings.

Note : This CSV time input (11-04-18 09:01 GMT}) coincides with the daylight switch on the default timezone configured:

Los Angeles
4 Nov 2018 - Daylight Saving Time Ended
When local daylight time was about to reach
Sunday, 4 November 2018, 02:00:00 clocks were turned backward 1 hour to
Sunday, 4 November 2018, 01:00:00 local standard time instead.

Workaround

Set the Default user time zone temporarily to System default GMT+0 and run the import