try use a different rust version

.circleci/config.yml

@@ -138,6 +138,8 @@ jobs:
     steps:
       - *restore-workspace
       - *restore-cache
+      - run: rustup install $(cat rust-toolchain)
+      - run: rustup default $(cat rust-toolchain)
       - run:
           name: build docs, run tests and build wheels
           command: ci_scripts/run-python.sh

rust-toolchain

@@ -1 +1 @@
-nightly-2019-09-12
+nightly-2019-11-06

src/e2ee.rs

@@ -498,7 +498,7 @@ fn decrypt_if_autocrypt_message(
     public_keyring_for_validate: &Keyring,
     ret_valid_signatures: &mut HashSet<String>,
     ret_gossip_headers: *mut *mut mailimf_fields,
-) -> Result<(bool)> {
+) -> Result<bool> {
     /* The returned bool is true if we detected an Autocrypt-encrypted
     message and successfully decrypted it. Decryption then modifies the
     passed in mime structure in place. The returned bool is false