Cannot reconnect GitHub repo using az cli: HTTP 500

**Describe the bug**

I want to change the branch name of the GitHub repo. Azure Portal doesn't allow to do that right now. Nor does ARM template:

> Branch is invalid. Cannot change the Branch. Please detach your static site first if you wish to attach to another branch

I was able to disconnect by running `az staticwebapp disconnect`. Now I'm trying to connect back by running `az staticwebapp reconnect`. However it fails with 500.

**To Reproduce**

```
az staticwebapp reconnect --name godfathernetru --branch html --source https://github.com/abatishchev/godfather.net.ru.git --login-with-github
Command group 'staticwebapp' is in preview and under development. Reference and support levels: https://aka.ms/CLI_refstatus
Please navigate to https://github.com/login/device and enter the user code 3DC9-2492 to activate and retrieve your github personal access token
Waiting up to '14' minutes for activation
Operation returned an invalid status 'Internal Server Error'
```

Git repo: https://github.com/abatishchev/godfather.net.ru
Branch: html

**Expected behavior**

It doesn't return 500.

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Device info (if applicable):**
- OS: Windows 10 build 19043
- Browser: Firefox 90.0.2
- Version:

```json
az version
{
"azure-cli": "2.26.1",
"azure-cli-core": "2.26.1",
"azure-cli-telemetry": "1.0.6",
"extensions": {
"azure-iot": "0.9.7"
}
}
```