Redash: Chart stacking sorting inconsistent

[JoshKeegan]

Issue Summary

This isn't necessarily a bug, but is unusual/unexpected behaviour and isn't consistent.
When making a chart, if stacking is disabled the key appears to be sorted ascending.
If the same chart (with exactly the same results) has stacking enabled, the key becomes sorted descending.

Steps to Reproduce

1. Make a chart with a table containing two categories and a number (so you can have an x, y and group by).
2. Toggle stacking.

Technical details:

• Redash Version: 3.0.0+b3134
• Browser/OS: Firefox 59.0.2, Windows 10
• How did you install Redash: Manually onto Debian

[JoshKeegan]

I've just installed the new 4.0 release and the key is now being sorted ascending, so this appears to have been fixed.
Cheers,
Josh