MacOS problem with special char in username and Finder integration

Hi.

I'm having issues with the Finder/File integration on MacOS Mojave. The issue is that my username is my email address (don't have a choice as it is setup by IT in the company I work for) and it seems that it causes issue with the Finder/File integration.
I'm getting:
```
$ ls -l /Volumes/Keybase
total 0
lr-xr-xr-x 1 root wheel 0 Feb 7 15:24 KBFS_NOT_RUNNING -> /dev/null
```
If I create another user on the same computer with a username with only letters, it works fine so I guess the problem is due to the special characters. I can also say that I can see some `The provided mount directory doesn't meet expectations: /Volumes/Keybase (first.last@example.com)` in the logs. And the directory with special char is not created:
```
$ ls -l /Volumes
total 0
dr-xr-xr-x 1 root wheel 0 Feb 7 15:24 Keybase
lrwxr-xr-x 1 root wheel 1 Feb 7 15:23 Macintosh HD -> /
```

Any ideas how I can work around this?

Start by reproducing the Finder/File integration on macOS with a username containing an email address, then inspect the logs for the reported mount-directory expectation error and compare the /Volumes entries with a letters-only username. Done means the integration mounts successfully for usernames with special characters without leaving the KBFS_NOT_RUNNING link.

Written by the indexing model from the issue text.