Description

I have enabled the search_all_users option for the user directory search (and applied the #2831 patch to fix the internal server error). I've found that the user directory search works very well except when searching for the single letters a, s, and t. Searching for other single letters of the alphabet produces the correct results.

Steps to reproduce

POST to https://matrix.floydcounty.tv/_matrix/client/r0/user_directory/search with the proper authentication and the following JSON body:

{
	"search_term": "t"
}

I expect to receive a list of users whose display name or username starts with the letter t (there would be at least 10 results on my server). Instead, I get an empty result:

{
    "limited": false,
    "results": []
}

POSTing with some other letter, for example j, will return a list of users as expected.

The homeserver log doesn't show anything unusual for this particular request.

Version information

• Version: Synapse/0.26.0
• Install method: pip
• Platform: Ubuntu 16.04.3 LTS running on a Xen VM