Merge branch 'ticket32629_041' into ticket32629_042

Merge RUST_VERSION from maint-0.4.2 with disabling the macOS Rust
job from ticket32629_041.

diff --cc .travis.yml
index 252da6877af3aa1496c1792aff3b9d0cc742b5d2,c56ced37b064e229c5077cf5595a20e543d91571..f386500b21edb144d6b9f282e615279892b24b77
--- 1/.travis.yml
--- 2/.travis.yml
+++ b/.travis.yml
@@@ -64,9 -62,11 +64,11 @@@ matrix
      - env: DISTCHECK="yes" ASCIIDOC_OPTIONS="" SKIP_MAKE_CHECK="yes"
      ## We check disable module dirauth
      - env: MODULES_OPTIONS="--disable-module-dirauth"
+     ## macOS builds are very slow, and we have a limited number of
+     ## concurrent macOS jobs. We're not actively developing Rust, so it is
+     ## the lowest priority.
      ## We run rust on macOS, because we have seen macOS rust failures before
-     # Disabled due to slow Travis macOS builds, see #32177
 -    #- env: RUST_OPTIONS="--enable-rust --enable-cargo-online-mode"
 +    #- env: RUST_VERSION="nightly" RUST_OPTIONS="--enable-rust --enable-cargo-online-mode"
      #  compiler: clang
      #  os: osx
      ## We run chutney on macOS, because macOS Travis has IPv6