Fix Batch Shipyard site extension upgrade (#113)

site-extension/batch-shipyard.nuspec

@@ -6,7 +6,7 @@
     <title>Batch Shipyard</title>
     <authors>Fred Park</authors>
     <requireLicenseAcceptance>true</requireLicenseAcceptance>
-    <description>Execute jobs on Azure Batch via Batch Shipyard. Requires Python.</description>
+    <description>Execute containerized jobs on Azure Batch via Batch Shipyard. Requires Python.</description>
     <iconUrl>https://azurecomcdn.azureedge.net/cvt-4c210654e280636c85b81aae4511f99613c7de5d03801bf44dc15fe823371003/images/page/services/batch/we-take-care-of-scale.png</iconUrl>
     <projectUrl>https://github.com/Azure/batch-shipyard</projectUrl>
     <licenseUrl>https://github.com/Azure/batch-shipyard/blob/master/LICENSE</licenseUrl>

site-extension/install.cmd

@@ -29,18 +29,19 @@ taskkill /F /IM python.exe
 SET CLONEDIR=%HOME%\batch-shipyard
 IF EXIST "%CLONEDIR%" (
     pushd "%CLONEDIR%"
-    git checkout master
-    git pull
+    git fetch --tags
+    git checkout %SHIPYARDVER%
     IF %ERRORLEVEL% NEQ 0 (
-        cd %HOME%
-        rd /s /q "%CLONEDIR%"
+        echo "Could not git fetch to tag %SHIPYARDVER% at %CLONEDIR%"
+        exit /b 1
     )
     popd
-)
-git clone --branch %SHIPYARDVER% "https://github.com/Azure/batch-shipyard.git" "%CLONEDIR%"
-IF %ERRORLEVEL% NEQ 0 (
-    echo "git clone failed"
-    exit /b 1
+) ELSE (
+    git clone --branch %SHIPYARDVER% "https://github.com/Azure/batch-shipyard.git" "%CLONEDIR%"
+    IF %ERRORLEVEL% NEQ 0 (
+        echo "Could not git clone to tag %SHIPYARDVER% at %CLONEDIR%"
+        exit /b 1
+    )
 )
 
 REM create cmd file