On http://sourceforge.net/p/sshpass/bugs/12/ the issue is explained:
Doing a "sshpass -p password ssh vmfreebsd10-32 -l account ls" hangs
forever. The reason is that in this combination the prompt for the
password looks like this: "Password for account@vmfreebsd10-32:" and
sshpass checks the password against the string "assword:", so there
is no match.
This is fixed upstream in trunk, but no release has been created yet.
Import the patch into the ports tree until the next release.
PR: 204819
Submitted by: andrey@bsdnir.info
Approved by: maintainer timeout
2d040a35a3