SASL password with space not being handled properly

I'm getting a SASL auth error using 'isasl' and libcouchbase.
The bucket is a memcached bucket with a password including a space in it "a password". When the password is changed to "a_password" it works fine.

Attached is the JSON bucket output (pools/defaults/buckets/memcached_bucket)

mnunberg@csure:/sources/libcouchbase$ /opt/couchbase/bin/couchbase-cli bucket-edit --cluster=10.3.121.209 --bucket-password="a password" -u Administrator -p 123456 --bucket="memcached_bucket"
SUCCESS: bucket-edit
mnunberg@csure:/sources/libcouchbase$ echo 'hi' | ./tools/cbc create -h 10.3.121.209 -u Administrator -P 123456 a_key -b memcached_bucketERROR: Authentication error
"SASL authentication failed"
mnunberg@csure:/sources/libcouchbase$ /opt/couchbase/bin/couchbase-cli bucket-edit --cluster=10.3.121.209 --bucket-password="a_password" -u Administrator -p 123456 --bucket="memcached_bucket"
SUCCESS: bucket-edit
mnunberg@csure:/sources/libcouchbase$ echo 'hi' | ./tools/cbc create -h 10.3.121.209 -u Administrator -P 123456 a_key -b memcached_bucketStored "a_key" CAS:100000000000000
mnunberg@csure:/sources/libcouchbase$