Merge #269

269: [v0.4.x] CI: pin to an older nightly r=korken89 a=japaric

to workaround compiletest-rs being broken on recent nightlies

this is a backport of #267 and it's required to land #265 

I'm not backporting #268  (compiletest -> trybuild) because this branch has compile-pass tests which depend on compiletest and can't be ported to trybuild

Co-authored-by: Jorge Aparicio <jorge@japaric.io>

.travis.yml

@@ -12,7 +12,8 @@ matrix:
 
     # NOTE used to build docs on successful merges to master
     - env: TARGET=x86_64-unknown-linux-gnu
-      rust: nightly
+      # FIXME revert this -- compiletest-rs v0.3.25 is broken with recent nightly
+      rust: nightly-2019-10-31
 
     - env: TARGET=thumbv6m-none-eabi
       rust: nightly