Label search doesn't work when label contains "#" char.

Details can be found in this Google document:
https://docs.google.com/document/d/179YhJJVUiogPXv_8QIFJXjRU_WZ5Y1UeLAj88Ywfksk/edit?usp=sharing

In short:
When searching for a label that has a "#", the search takes forever and never returns any result.

Severity:
This is a problem for us because all our test have at least one "formal" label. A "formal" label starts with "#". If we can't use this search our productivity goes down.