Filtering issues by label in a specific milestone is not possible

[sv-calin]

Url: https://webcompat.com/issues

Environment: Operating system: Windows 10 Firefox version: Nightly 104.0a1 (2022-07-17) (64-bit)

Steps to reproduce:

1. Go to https://webcompat.com/issues
2. Click on any milestone in order to select it
3. Type any label in the search bar (eg. "label:engine-gecko")
4. Press "Enter"
5. Observe the result

Expected Behavior: Filtering issues by label in a specific milestone is possible.

Actual Behavior: Filtering issues by label in a specific milestone is not possible, the label returns issues across all the milestones. The milestone is deselected.

Notes:

1. Video provided https://gifyu.com/image/SNpZ6
2. Reproducible on Chrome as well
3. Selecting a different milestone and applying the same label won't do anything (works if you apply a different label): https://gifyu.com/image/SNpaB

Watchers: @softvision-oana-arbuzov @softvision-raul-bucata @ClintNase

[karlcow]

It goes from https://webcompat.com/issues?page=1&per_page=50&state=open&stage=needsdiagnosis&sort=created&direction=desc

to

https://webcompat.com/issues?page=1&per_page=50&state=open&stage=all&sort=created&direction=desc&q=label%3Aengine-gecko

stage parameter switched from needsdiagnosis to all

[karlcow]

https://github.com/webcompat/webcompat.com/blob/67f2831bd6a12a157a44ec165590f0b8edb03c31/webcompat/static/js/lib/models/issue.js#L154-L167