python-pyasn1 is truly optional since version 2.5.0 and
https://github.com/paramiko/paramiko/commit/a31818c28556055341ae3d249e3893d40eb2b232
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 78da0a0ea3)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>