Merge branch 'IxAsyncCSharp8' of https://github.com/dotnet/reactive into IxAsyncCSharp8

.gitignore

@@ -185,3 +185,6 @@ nuget.exe
 
 # dotnet local cache
 .dotnet
+
+# JetBrains Rider adds these
+.idea/

azure-pipelines.ix.yml

@@ -14,6 +14,7 @@ pr:
     include:
       - master
       - rel/*
+      - IxAsyncCSharp8
   paths:
     include:
       - Ix.NET/Source/*