$ kinit admin
$ ipa user-add myuser --first myuser --last myuser

$ ipa cert-request  --principal myuser --database /tmp/nssdb
/usr/lib/python3.6/site-packages/ipaclient/csrgen.py:464: BytesWarning: str() on a bytes instance
  ['certutil', '-S', '-n', self.nickname, '-s', 'CN=%s' % temp_cn,
Enter Password or Pin for "NSS Certificate DB":

A random seed must be generated that will be used in the
creation of your key.  One of the easiest ways to create a
random seed is to use the timing of keystrokes on a keyboard.

To begin, type keys on the keyboard until this progress meter
is full.  DO NOT USE THE AUTOREPEAT FUNCTION ON YOUR KEYBOARD!


Continue typing until the progress meter is full:

|************************************************************|

Finished.  Press enter to continue:


Generating key.  This may take a few moments...

/usr/lib/python3.6/site-packages/ipaclient/plugins/cert.py:135: BytesWarning: str() on a bytes instance
public_key_info=unicode(pubkey_info_b64))
ipa: ERROR: non-public: Error: Incorrect padding
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/ipalib/backend.py", line 142, in execute
    result = self.Command[_name](*args, **options)
  File "/usr/lib/python3.6/site-packages/ipalib/frontend.py", line 450, in __call__
    return self.__do_call(*args, **options)
  File "/usr/lib/python3.6/site-packages/ipalib/frontend.py", line 478, in __do_call
    ret = self.run(*args, **options)
  File "/usr/lib/python3.6/site-packages/ipalib/frontend.py", line 801, in run
    return self.forward(*args, **options)
  File "/usr/lib/python3.6/site-packages/ipaclient/plugins/cert.py", line 135, in forward
    public_key_info=unicode(pubkey_info_b64))
  File "/usr/lib/python3.6/site-packages/ipalib/frontend.py", line 450, in __call__
    return self.__do_call(*args, **options)
  File "/usr/lib/python3.6/site-packages/ipalib/frontend.py", line 478, in __do_call
    ret = self.run(*args, **options)
  File "/usr/lib/python3.6/site-packages/ipalib/frontend.py", line 1202, in run
    return self.forward(*args, **options)
  File "/usr/lib/python3.6/site-packages/ipalib/frontend.py", line 1205, in forward
    return self.execute(*args, **options)
  File "/usr/lib/python3.6/site-packages/ipaclient/plugins/csrgen.py", line 90, in execute
    public_key_info = base64.b64decode(public_key_info)
  File "/usr/lib64/python3.6/base64.py", line 87, in b64decode
    return binascii.a2b_base64(s)
binascii.Error: Incorrect padding
ipa: ERROR: an internal error has occurred