Fix UnlockOnActivity for concurrent requests

[ExtraClock]

Hello!

Here is a fix for scenario when database is locked and multiple requests are being sent to the agent. For example, if you have a git repo with multiple ssh remotes, and you do a "fetch all remotes" in your IDE.

It is easily reproduced with multiple ssh-add -l commands thrown at the agent.

Behavior before fix:

• One password prompt is shown
• Only first "ssh-add -l" request is granted
• Subsequent requests receive an empty list of keys

Behavior after fix:

• One password prompt is shown
• All of the request are granted with a correct list of keys

[dlech]

Thanks!