fix old version vsts-task-lib to not overwrite (#993)
fix old version vsts-task-lib to not overwrite (#993)

string.startswith/endswith.
lkillgore/vsts-agent,lkillgore/vsts-agent,kasubram/vsts-agent,kasubram/vsts-agent,Microsoft/vsts-agent,Microsoft/vsts-agent,kasubram/vsts-agent,lkillgore/vsts-agent,lkillgore/vsts-agent,Microsoft/vsts-agent,Microsoft/vsts-agent,kasubram/vsts-agent