Attempt to fix appveyor build

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@302084 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/appveyor.yml b/appveyor.yml
index 3cb2ce6..9312088 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -8,10 +8,6 @@
 build:
   verbosity: detailed
 
-branches:
-  only:
-    - master
-
 configuration:
   - Debug