guess() breaking change with node 10

[feugy]

Hello!

We recently experienced a "breaking" change while upgrading to latest Node.js:

$ nvm use v8.11.1
Now using node v8.11.1 (npm v5.6.0)

$ TZ=Universal node -e "const m = require('moment-timezone'); console.log(m.utc().tz(m.tz.guess()).zoneAbbr())"
UTC

$ TZ=Universal node -e "const m = require('moment-timezone'); console.log(m.tz.guess())"
Etc/UTC



$ nvm use v10.12.0
Now using node v10.12.0 (npm v6.4.1)

$ TZ=Universal node -e "const m = require('moment-timezone'); console.log(m.utc().tz(m.tz.guess()).zoneAbbr())"
GMT

$ TZ=Universal node -e "const m = require('moment-timezone'); console.log(m.tz.guess())"
Africa/Abidjan

In both cases, the intlName returned by rebuildGuess() is 'UTC', but I found that userOffsets() returns something completely different:

# node 10
[ OffsetAt { at: 1451606400000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1451606400000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1467331200000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1483228800000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1498867200000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1514764800000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1530403200000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1546300800000, abbr: undefined, offset: 0 },
  OffsetAt { at: 1561939200000, abbr: undefined, offset: 0 } ]

# node 8
[ OffsetAt { at: 1451606400000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1451606400000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1467331200000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1483228800000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1498867200000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1514764800000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1530403200000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1546300800000, abbr: 'UTC', offset: 0 },
  OffsetAt { at: 1561939200000, abbr: 'UTC', offset: 0 } ]

When setting a different timezone with TZ env variable, results are consistent.

Any clue?
(I'm working from Europe/Paris, but friend from Europe/London is experiencing the same).

[feugy]

Up?

[rnegron]

We are running into this issue as well. Any news?

[ichernev]

Is this still an issue?