No data for GMT-X timezones after updating

[9dev]

I followed the contributing guide and discovered that the first step is wiping some data out.

In the original repo file /data/unpacked/latest.json contains data for timezones like Etc/GMT+10, but after running grunt data these data become empty arrays with no information at all.

Steps to reproduce:

• Pull the recent version of the moment-timezone
• > npm install
• > grunt data

Is there a step missing in the guide to obtain the data for these timezones?

[gilmoreorless]

I found several discrepancies in how zdump produces output across different systems, and how our build system handled it. On some Linux flavours it resulted in fixed-offset zones being reported as the same as UTC.

I've (hopefully) fixed that with #1059. 🤞