Revert "Fix a bug loading v2 lockfiles"

This reverts commit c4b53c9.

Author: alexcrichton

src/cargo/ops/resolve.rs

@@ -15,12 +15,10 @@ use crate::core::registry::PackageRegistry;
 use crate::core::resolver::features::{
     FeatureOpts, FeatureResolver, ForceAllTargets, ResolvedFeatures,
 };
-use crate::core::resolver::{self, HasDevUnits, Resolve, ResolveOpts, ResolveVersion};
+use crate::core::resolver::{self, HasDevUnits, Resolve, ResolveOpts};
 use crate::core::summary::Summary;
 use crate::core::Feature;
-use crate::core::{
-    GitReference, PackageId, PackageIdSpec, PackageSet, Source, SourceId, Workspace,
-};
+use crate::core::{PackageId, PackageIdSpec, PackageSet, Source, SourceId, Workspace};
 use crate::ops;
 use crate::sources::PathSource;
 use crate::util::errors::{CargoResult, CargoResultExt};
@@ -601,31 +599,7 @@ fn register_previous_locks(
             .deps_not_replaced(node)
             .map(|p| p.0)
             .filter(keep)
-            .collect::<Vec<_>>();
-
-        // In the v2 lockfile format and prior the `branch=master` dependency
-        // directive was serialized the same way as the no-branch-listed
-        // directive. Nowadays in Cargo, however, these two directives are
-        // considered distinct and are no longer represented the same way. To
-        // maintain compatibility with older lock files we register locked nodes
-        // for *both* the master branch and the default branch.
-        //
-        // Note that this is only applicable for loading older resolves now at
-        // this point. All new lock files are encoded as v3-or-later, so this is
-        // just compat for loading an old lock file successfully.
-        if resolve.version() <= ResolveVersion::V2 {
-            let source = node.source_id();
-            if let Some(GitReference::DefaultBranch) = source.git_reference() {
-                let new_source =
-                    SourceId::for_git(source.url(), GitReference::Branch("master".to_string()))
-                        .unwrap()
-                        .with_precise(source.precise().map(|s| s.to_string()));
-
-                let node = node.with_source_id(new_source);
-                registry.register_lock(node, deps.clone());
-            }
-        }
-
+            .collect();
         registry.register_lock(node, deps);
     }