core: wait for build to get scheduling when follow
core: wait for build to get scheduling when follow

Fixes #113

jpopelka/osbs-client,DBuildService/osbs-client,bfontecc007/osbs-client,vrutkovs/osbs-client,twaugh/osbs-client,twaugh/osbs-client,pbabinca/osbs,DBuildService/osbs-client,pombredanne/osbs-client,pbabinca/osbs,bfontecc007/osbs-client,jpopelka/osbs-client,projectatomic/osbs-client,pombredanne/osbs-client,projectatomic/osbs-client,vrutkovs/osbs-client