/take can assign the wrong player

**Describe the bug**
When `Louis` is a player's leader name and `louis` is a username, and `louis` is connected, doing
```
/take lou lou
```
assigns username `lou` to player `Louis`.

**To Reproduce**

See above.

**Expected behavior**

Username `louis` controls player `Louis`

**Platform and version (please complete the following information):**
 - OS: Linux
 - Freeciv21 version: 3.1.0
