The version installed is conflicting with the version required in
testtools-1.7

While a better solution is to dig through and figure out what is causing
the transitive floating dependency that installs testtools 1.7
this should fix the issue for stable/icehouse. And we need to fix
stable/icehouse to fix stable/juno (because grenade) which in tern is
needed to unbreak master branch.

Change-Id: Ib193e18afbb60c43d8dd66444bbf367689837182
Partial-Bug: #1430592