Add more retries in case of manifest conflicts (many builders) and fix bug.
Add more retries in case of manifest conflicts (many builders) and fix bug.

Saw that every now and then 2 isn't enough, so let's just be safe and up
the retry # to 5.  In addition, I found a bug with local testing where
if there is nothing found to build, we error out.  This is wrong.

BUG=None
TEST=Ran with mario on TOT and branch.

Change-Id: I387e61df3eb2fb704498c9aeaf8453f1a77a5654
Reviewed-on: http://gerrit.chromium.org/gerrit/1991
Reviewed-by: David McMahon <d7a8ce96a624b268d0a29e63bafad5dd5091190e@chromium.org>
Tested-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>

coreos/chromite,zhang0137/chromite,zhang0137/chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,zhang0137/chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,coreos/chromite