[BUG] Tag object array result for GroupByTags

[evdevk]

Related to #755

this bug is still around in latest 0.16.1 link

typical request without alias like:
seriesByTag('name=system.system.load5', 'host=server1234')
works ok. response tags array looks like:

tags:Object
    contur:"prod"
    host:"server1234"
    interval:"15s"
    ostype:"linux"

same request with groupbytags:
groupByTags(seriesByTag('name=system.system.load5', 'host=server1234'), 'max', 'host')

have response array like this:

tags:Object
   host:"server1234"
   name:"max"

with older versions 0.15.5 works ok.

[npazosmendez]

groupByTags aggregates together multiple series that have the same values for a specific set of tags. Each of the series may have other tags too, but are discarded because not all series in a group may have the same values for those other tags.

The weird thing I see is how we name name:"max", that's not what Graphite Web does: https://github.com/graphite-project/graphite-web/blob/0ec7201c42ac2c14485c4c7eaab8a644082dc687/webapp/graphite/render/functions.py#L5801

[evdevk]

ok if it working as intended, as workaround I can add tags as argument in GroupByTags to get it as result

[Civil]

In this case "intended" = like in graphite-web

If current behavior mimics graphtie-web - that probably means if there will be a fix - it would be under its own feature flag, and I would work on that at low priority (taking into account amount of open issues and amount of free time I'm spending on the project now - likely never), but PRs that changes behavior under feature flag are welcome, I would gladly merge something like that if it doesn't change default behavior for people.