Update rust toolchain to 2020-04-20

This fixes rust-lang/rust#69933

Author: Thomas Scholtes

.buildkite/pipeline.yaml

@@ -3,7 +3,7 @@
   command: "ci/run"
   timeout_in_minutes: 60
   env:
-    DOCKER_IMAGE: gcr.io/opensourcecoin/radicle-registry/ci-base:9956955f61e2c91fb94a2ed4eee26bf17aa44b50
+    DOCKER_IMAGE: gcr.io/opensourcecoin/radicle-registry/ci-base:does_not_exist
     DOCKER_FILE: ci/base-image/Dockerfile
     STEP_DOCKER_FILE: ci/node-image/Dockerfile
     STEP_DOCKER_IMAGE: gcr.io/opensourcecoin/radicle-registry/node

ci/base-image/Dockerfile

@@ -2,7 +2,7 @@
 #
 # Includes
 #
-# * Rustup with `nightly-2020-03-19` toolchain (see RUST_VERSION)
+# * Rustup with `nightly-2020-04-20` toolchain (see RUST_VERSION)
 # * Additional rustup components and the wasm32 target
 # * sccache v0.2.12
 
@@ -42,7 +42,7 @@ RUN set -euxo pipefail; \
 
 # Install rustup and default toolchain from RUST_VERSION. This is copied from
 # https://github.com/rust-lang/docker-rust/blob/8d0f25416858e2c1f59511a15c2bd0445b402caa/1.39.0/buster/slim/Dockerfile
-ENV RUST_VERSION=nightly-2020-03-19
+ENV RUST_VERSION=nightly-2020-04-20
 RUN set -eux; \
     dpkgArch="$(dpkg --print-architecture)"; \
     case "${dpkgArch##*-}" in \

rust-toolchain

@@ -1 +1 @@
-nightly-2020-03-19
+nightly-2020-04-20