Merge remote-tracking branch 'isis/bug26398'

diff --cc src/rust/crypto/Cargo.toml
index 869e0d62566e04933014cb299c17bf6608b7a005,c31c8e185a713cf8fc84fa2c2595f1a259d349c2..d68ac48e28a69dc73848fb81db1cc4a1a059eb86
--- 1/src/rust/crypto/Cargo.toml
--- 2/src/rust/crypto/Cargo.toml
+++ b/src/rust/crypto/Cargo.toml
@@@ -26,3 -25,9 +26,7 @@@ rand = { version = "=0.5.0-pre.2", defa
  rand_core = { version = "=0.2.0-pre.0", default-features = false }
  
  [features]
 -testing = ["tor_log/testing"]
+ # If this feature is enabled, test code which calls Tor C code from Rust will
+ # execute with `cargo test`.  Due to numerous linker issues (#25386), this is
+ # currently disabled by default.
+ test-c-from-rust = []
 -

diff --cc src/rust/crypto/digests/sha2.rs
index 03e0843dc0851fcdb2352861818ee7db9fbe5843,bb610ed9e219fc4e627b78202b9f9410e26f9c21..d0246eeb94c889c941a6fc9cb8be890cf53c5217
--- 1/src/rust/crypto/digests/sha2.rs
--- 2/src/rust/crypto/digests/sha2.rs
+++ b/src/rust/crypto/digests/sha2.rs
@@@ -190,9 -191,10 +194,10 @@@ mod test 
  
          println!("{:?}", &result[..]);
  
 -        assert_eq!(&result[..], &b"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"[..]);
 +        assert_eq!(result, expected);
      }
  
+     #[cfg(feature = "test-c-from-rust")]
      #[test]
      fn sha512_default() {
          let _: Sha512 = Sha512::default();