Strip whitespace from the image version on Windows before using it.
diff --git a/buildkite/startup-windows.ps1 b/buildkite/startup-windows.ps1
index fed25eb..cebaa99 100755
--- a/buildkite/startup-windows.ps1
+++ b/buildkite/startup-windows.ps1
@@ -48,7 +48,7 @@
Remove-Item $buildkite_agent_token_file
## Get the current image version.
-$image_version = Get-Content "c:\buildkite\image.version" -Raw
+$image_version = (Get-Content "c:\buildkite\image.version" -Raw).Trim()
## Configure the Buildkite agent.
Write-Host "Configuring Buildkite Agent..."