Windows: Pre-flight check fails when user is 'SYSTEM'
Windows: Pre-flight check fails when user is 'SYSTEM'

When salt.utils.get_user() returns 'SYSTEM', as is the case when
salt-master is running as a Windows service:

os.path.expanduser('~' + salt.utils.get_user())
returns something like: 'C:\Windows\system32\config\SYSTEM'
Unfortunately, this is a file (not a folder) that already exists on the
system, causing the pre-flight checks to fail.

os.path.expanduser('~') returns something like:
'C:\WINDOWS\system32\config\systemprofile'
which is correct for the 'SYSTEM' user.

Signed-off-by: Sergey Kizunov <dfddabaa9af05982b01940b837a87844148069c9@ni.com>

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt