manual submodule clone

azure-pipelines.yml

@@ -7,6 +7,7 @@ jobs:
     inputs:
       version: '2.1.403'
   - script: |
+      git submodule update --init
       export COREHOST_TRACE=0
       export DOTNET_SKIP_FIRST_TIME_EXPERIENCE=1
       export DOTNET_CLI_TELEMETRY_OPTOUT=1
@@ -22,6 +23,7 @@ jobs:
     inputs:
       version: '2.1.403'
   - script: |
+      git submodule update --init
       export COREHOST_TRACE=0
       export DOTNET_SKIP_FIRST_TIME_EXPERIENCE=1
       export DOTNET_CLI_TELEMETRY_OPTOUT=1
@@ -37,6 +39,7 @@ jobs:
     inputs:
       version: '2.1.403'
   - script: |
+      git submodule update --init
       set COREHOST_TRACE=0
       set DOTNET_SKIP_FIRST_TIME_EXPERIENCE=1
       set DOTNET_CLI_TELEMETRY_OPTOUT=1