Cannot use non-ASCII password on certificate

[dwmw2]

This ought to work, but doesn't:

$ openconnect -v -c ~/git/openconnect/tests/certs/user-key-nonascii-password.p12 facebook.com --key-password ĂŻ
POST https://facebook.com/
Attempting to connect to server 31.13.92.36:443
Connected to 31.13.92.36:443
Using certificate file /home/local/ANT/dwmw/git/openconnect/tests/certs/user-key-nonascii-password.p12
Failed to process PKCS#12 file: The given password contains invalid characters.
Loading certificate failed: No certificate found in file
Loading certificate failed. Aborting.
Failed to open HTTPS connection to facebook.com
Failed to obtain WebVPN cookie

[dwmw2 (dwmw2)]

The above was on Ubuntu 16.04 with 3.4.10-4ubuntu1.3