Merge pull request #245 from thaJeztah/18.09_backport_allow_version_overwrite

[18.09 backport] Add ability to override the version in make.ps1
Upstream-commit: f07e4693278434c112870d30d80ad984bc79e527
Component: engine

components/engine/hack/make.ps1

@@ -351,6 +351,8 @@ Try {
 
     # Get the version of docker (eg 17.04.0-dev)
     $dockerVersion="0.0.0-dev"
+    # Overwrite dockerVersion if VERSION Environment variable is available
+    if (Test-Path Env:\VERSION) { $dockerVersion=$env:VERSION }
 
     # Give a warning if we are not running in a container and are building binaries or running unit tests.
     # Not relevant for validation tests as these are fine to run outside of a container.