Labels starting with an underscore cannot be used as filters

[javsjmoore]

Describe the bug Attempting to subscribe to a repo using a label filter that starts with an underscore results in the following message: +label:_myLabel is not a valid argument. The right format is +label:"my label"

To Reproduce Attempt any of the following in the GitHub teams chat channel after installing the GitHub/Teams app integration:

1. subscribe owner/repo +label:_myLabel
2. subscribe owner/repo +label:"_myLabel"

Expected behavior The subscribing user receives the following response:

This channel will receive notifications from owner/repo for issues, pulls, commits, comments, releases, deployments, +label:'_myLabel'

Desktop (please complete the following information):

• OS: Windows 10 Pro build 19042.1348
• Browser: Chrome Version 95.0.4638.69 (Official Build) (64-bit)
• Microsoft Teams Version 1.4.00.29469 (64-bit)

Additional context I receive the same results for repos in my org and my personal, private repos. I have confirmed removing the underscore allows the filter to be added.

I'm aware the documentation mentions special characters but doesn't get very specific of what it does and doesn't support.

It is common to have certain special characters in labels. Therefore we added support for the most common special characters for label filters. Here a few examples: label:priority:HIGH label:teams/designers label:"DO NOT MERGE" label:"very important" label:"🚧 WIP"

[ashokirla]

@snankani Can you please get the DRI to look into this issue.

[hargut]

Looks like this is the case for all labels including "_".

GitHub subscribe <owner>/<repo> +label:"version_update"
+label:"version_update" is not a valid argument. The right format is +label:"my label"