Use XPath in Get-VersionCore so the implementation is more robust

build/Targets/Packages.props

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright (c)  Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information. -->
-<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project>
 
   <PropertyGroup>
     <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>

build/Targets/Tools.props

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright (c)  Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information. -->
-<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project>
 
   <PropertyGroup>
     <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>

build/scripts/build-utils.ps1

@@ -245,12 +245,9 @@ function Get-VersionCore([string]$name, [string]$versionFile) {
     $name = $name.Replace("-", "")
     $nodeName = "$($name)Version"
     $x = [xml](Get-Content -raw $versionFile)
-    $node = $x.Project.PropertyGroup.FirstChild
-    while ($node -ne $null) {
-        if ($node.Name -eq $nodeName) {
-            return $node.InnerText
-        }
-        $node = $node.NextSibling
+    $node = $x.SelectSingleNode("//Project/PropertyGroup/$nodeName")
+    if ($node -ne $null) {
+        return $node.InnerText
     }
 
     throw "Cannot find package $name in $versionFile"