Workaround a clippy bug (#324)

* ineffective as a lasersight on a shotgun; but makes clippy work

* toolchain is mentioned in the cmd

.gitlab-ci.yml

@@ -124,7 +124,7 @@ clippy-std:
     - check-std
   script:
     - for crate in ${ALL_CRATES}; do
-        cargo clippy --verbose --all-features --manifest-path ${crate}/Cargo.toml -- -D warnings;
+        cargo +nightly-2020-02-01 clippy --verbose --all-features --manifest-path ${crate}/Cargo.toml -- -D warnings;
       done
 
 clippy-wasm:
@@ -134,7 +134,7 @@ clippy-wasm:
     - check-wasm
   script:
     - for crate in ${ALL_CRATES}; do
-        cargo clippy --verbose --no-default-features --manifest-path ${crate}/Cargo.toml --target wasm32-unknown-unknown -- -D warnings;
+        cargo +nightly-2020-02-01 clippy --verbose --no-default-features --manifest-path ${crate}/Cargo.toml --target wasm32-unknown-unknown -- -D warnings;
       done
 
 fmt:
@@ -172,7 +172,7 @@ examples-clippy-std:
   <<:                              *docker-env
   script:
     - for example in examples/*/; do
-        cargo clippy --verbose --manifest-path ${example}/Cargo.toml -- -D warnings;
+        cargo +nightly-2020-02-01 clippy --verbose --manifest-path ${example}/Cargo.toml -- -D warnings;
       done
 
 examples-clippy-wasm:
@@ -180,7 +180,7 @@ examples-clippy-wasm:
   <<:                              *docker-env
   script:
     - for example in examples/*/; do
-        cargo clippy --verbose --manifest-path ${example}/Cargo.toml --no-default-features --target wasm32-unknown-unknown -- -D warnings;
+        cargo +nightly-2020-02-01 clippy --verbose --manifest-path ${example}/Cargo.toml --no-default-features --target wasm32-unknown-unknown -- -D warnings;
       done
 
 examples-contract-build: