Add detail to multiple rename deps

Cargo.toml

@@ -28,7 +28,7 @@ curl = { version = "0.4.19", features = ['http2'] }
 curl-sys = "0.4.15"
 env_logger = "0.6.0"
 pretty_env_logger = { version = "0.3", optional = true }
-failure = "0.1.2"
+failure = "0.1.5"
 filetime = "0.2"
 flate2 = { version = "1.0.3", features = ['zlib'] }
 fs2 = "0.4"

src/cargo/core/resolver/resolve.rs

@@ -240,14 +240,11 @@ unable to verify that `{0}` is the same as when the lockfile was generated
         });
         let name = names.next().unwrap_or_else(|| crate_name.clone());
         for n in names {
-            if n == name {
-                continue;
-            }
-            failure::bail!(
-                "multiple dependencies listed for the same crate must \
-                 all have the same name, but the dependency on `{}` \
-                 is listed as having different names",
-                to
+            failure::ensure!(
+                n == name,
+                "the crate `{}` depends on crate `{}` multiple times with different names",
+                from,
+                to,
             );
         }
         Ok(name)

tests/testsuite/rename_deps.rs

@@ -186,8 +186,7 @@ fn rename_twice() {
 [UPDATING] `[..]` index
 [DOWNLOADING] crates ...
 [DOWNLOADED] foo v0.1.0 (registry [..])
-error: multiple dependencies listed for the same crate must all have the same \
-name, but the dependency on `foo v0.1.0` is listed as having different names
+error: the crate `test v0.1.0 ([CWD])` depends on crate `foo v0.1.0` multiple times with different names
 ",
         )
         .run();