samba tool - tests: Fix shell metacharacters in generated password
Restrict the random password to [A-Za-z0-9] to ensure there are no shell
metacharacters in the generated password.
The tests use "samba-tool user create" to create the test user.
Occasionally the generated password contained shell metachatacters and
the command failed.
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri Jun 9 09:50:28 CEST 2017 on sn-devel-144