[Globals] Defining breakpoints in site.variables in a custom packaged theme not building

[trandromeda]

Bug Report

Steps to reproduce

1. Create a custom packaged theme by making a new folder under themes e.g. semantic/src/themes/mycustomtheme
2. Create mycustomtheme/globals/site.variables
3. Add your own breakpoints e.g.

@mobileBreakpoint            : 320px;
@tabletBreakpoint            : 958px;
@computerBreakpoint          : 1182px;
@largeMonitorBreakpoint      : 1360px;
@widescreenMonitorBreakpoint : 1920px;

4. In theme.config, specify Globals: @site to use the custom theme e.g. @site : 'mycustomtheme';
5. Run gulp build

Expected result

Site should use new breakpoint values

Actual result

Site ignores breakpoint values in custom theme's site.variables, instead uses the values of the last theme that was specified in Globals: @site.

Testcase

(unable to demonstrate this in a jsfiddle)
You can replicate using this simple UI to view different breakpoint behaviours (cards span full width under tablet size):

<div class="ui four column grid stackable cards">
  <div class="ui fluid card">
  A card
  </div>
    <div class="ui fluid card">
  A card
  </div>
    <div class="ui fluid card">
  A card
  </div>
    <div class="ui fluid card">
  A card
  </div>
    <div class="ui fluid card">
  A card
  </div>
    <div class="ui fluid card">
  A card
  </div>
</div>

• setting another one of the pre-packaged themes in Globals: @site, such as Github or Amazon, will correctly set the breakpoints
• custom breakpoints work when setting them in the Site Theme
• if making changes to site.variables of the custom theme, gulp watch will not be triggered

Version

2.7.8

[trandromeda]

I just found this in tasks/build/css.js:223:

      if(path.indexOf('site.variables') !== -1)  {
        return;
      } 

So any changes to a site.variables file is ignored and not built... that would explain why my custom theme globals for site.variables were not being used. From this, it seems the intent of the author was to enforce usage of site globals only to the Site Theme ...? It confused me that the Github, Amazon and Material themes had a Globals/site.variables file, so I was thinking I could do the same for a custom theme. Would appreciate some clarification on this matter, thanks!

[exoego]

@ColinFrick
Could you see this when you have time ?
I think you have expertise in build tools.

[ColinFrick]

I'll look into it.