skip Miri tests if the setup fails

Author: RalfJung

ci/miri.sh

@@ -5,7 +5,6 @@ set -ex
 export CARGO_NET_RETRY=5
 export CARGO_NET_TIMEOUT=10
 
-if rustup component add miri ; then
-    cargo miri setup
+if rustup component add miri && cargo miri setup ; then
     cargo miri test -- -- -Zunstable-options --exclude-should-panic
 fi