not really part of this PR, but while we're here, is there a reason we tell users that

1. we use pexpect
2. we ship a version of pexpect in external
3. we use installed version of Pexpect of one exists
4. here's how to install pexect.

It seems to me that we Should get rid of 4, and reorder the others to be to go: 1,3,2, no?