fix(vendor): Don't vendor builtins

Author: adamgemmell

src/ops/cargo_vendor.rs

@@ -154,10 +154,10 @@ fn sync(
             .with_context(|| format!("failed to load lockfile for {}", ws.root().display()))?;
 
         packages
-            .get_many(resolve.iter())
+            .get_many(resolve.iter().filter(|pkg| !pkg.source_id().is_builtin()))
             .with_context(|| format!("failed to download packages for {}", ws.root().display()))?;
 
-        for pkg in resolve.iter() {
+        for pkg in resolve.iter().filter(|pkg| !pkg.source_id().is_builtin()) {
             let sid = source_replacement_cache.get(pkg.source_id())?;
 
             // Don't vendor path crates since they're already in the repository

tests/testsuite/standard_lib.rs

@@ -513,7 +513,6 @@ fn builtins_do_not_show_in_tree() {
         .run();
 }
 
-#[ignore = "vendoring tries to vendor builtins, and fails"]
 #[cargo_test(build_std_mock)]
 fn builtins_are_not_vendored() {
     let setup = setup();