Trigger another Teamcity build as a build step (because Teamcity triggers lose the triggeredBy environmental variable)

teamcity-trigger-build.ps1

# Trigger the acceptance tests
# Docs: https://confluence.jetbrains.com/display/TCD8/REST+API#RESTAPI-TriggeringaBuild

$branchName = "%teamcity.build.branch%"
$url = "http://teamcity.mydomain.com:8500/guestAuth/app/rest/buildQueue"
$buildId = "%system.teamcity.buildType.id%"
$buildId = $buildId.Replace("_Deploy", "_AcceptanceTests")

$webClient = New-Object net.webclient

try {  
    $xml = "<build branchName=`"$branchName`"><buildType id=`"$buildId`"/></build>"
    Write-host "Sending this xml to $url : $xml"

    $webClient.Headers.Add("Content-Type", "application/xml")
    $webClient.UploadString($url, $xml) | write-host "ok"
}
catch {
    Write-Host "Looks like this project doesn't have acceptance tests, ignoring."
    exit 0
}