diff --git a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
index 5575e74..8072b3a 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
@@ -40,16 +40,17 @@
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Objects;
 import javax.annotation.Nullable;
 
 /**
  * An Artifact represents a file used by the build system, whether it's a source
  * file or a derived (output) file. Not all Artifacts have a corresponding
- * FileTarget object in the <code>build.packages</code> API: for example,
+ * FileTarget object in the <code>build.lib.packages</code> API: for example,
  * low-level intermediaries internal to a given rule, such as a Java class files
  * or C++ object files. However all FileTargets have a corresponding Artifact.
  *
- * <p>In any given call to Builder#buildArtifacts(), no two Artifacts in the
+ * <p>In any given call to SkyframeExecutor#buildArtifacts(), no two Artifacts in the
  * action graph may refer to the same path.
  *
  * <p>Artifacts generally fall into two classifications, source and derived, but
@@ -191,10 +192,10 @@
    * </pre>
    *
    * <p>In a derived Artifact, the execPath will overlap with part of the root, which in turn will
-   * be below of the execRoot.
+   * be below the execRoot.
    * <pre>
    *  [path] == [/root][pathTail] == [/execRoot][execPath] == [/execRoot][rootPrefix][pathTail]
-   * <pre>
+   * </pre>
    */
   @VisibleForTesting
   public Artifact(Path path, Root root, PathFragment execPath, ArtifactOwner owner) {
@@ -407,7 +408,7 @@
    * @see SpecialArtifact
    */
   @VisibleForTesting
-  public static enum SpecialArtifactType {
+  public enum SpecialArtifactType {
     FILESET,
     TREE,
     CONSTANT_METADATA,
@@ -604,7 +605,7 @@
     // We don't bother to check root in the equivalence relation, because we
     // assume that no root is an ancestor of another one.
     Artifact that = (Artifact) other;
-    return this.path.equals(that.path);
+    return Objects.equals(this.path, that.path);
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java b/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java
index bba4928..7d187f9 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java
@@ -288,7 +288,8 @@
    * lives in a subpackage distinct from that of baseExecPath, and {@code baseRoot} otherwise.
    */
   public synchronized Artifact resolveSourceArtifactWithAncestor(
-      PathFragment relativePath, PathFragment baseExecPath, Root baseRoot) {
+      PathFragment relativePath, PathFragment baseExecPath, Root baseRoot,
+      RepositoryName repositoryName) {
     Preconditions.checkState(
         (baseExecPath == null) == (baseRoot == null),
         "%s %s %s",
@@ -313,7 +314,8 @@
       return null;
     }
 
-    return createArtifactIfNotValid(findSourceRoot(execPath, baseExecPath, baseRoot), execPath);
+    return createArtifactIfNotValid(
+        findSourceRoot(execPath, baseExecPath, baseRoot, repositoryName), execPath);
   }
 
   /**
@@ -322,22 +324,21 @@
    */
   @Nullable
   private Root findSourceRoot(
-      PathFragment execPath, @Nullable PathFragment baseExecPath, @Nullable Root baseRoot) {
+      PathFragment execPath, @Nullable PathFragment baseExecPath, @Nullable Root baseRoot,
+      RepositoryName repositoryName) {
     PathFragment dir = execPath.getParentDirectory();
     if (dir == null) {
       return null;
     }
 
-    RepositoryName repoName = RepositoryName.MAIN;
-
     Pair<RepositoryName, PathFragment> repo = RepositoryName.fromPathFragment(dir);
     if (repo != null) {
-      repoName = repo.getFirst();
+      repositoryName = repo.getFirst();
       dir = repo.getSecond();
     }
 
     while (dir != null && !dir.equals(baseExecPath)) {
-      Root sourceRoot = packageRoots.get(PackageIdentifier.create(repoName, dir));
+      Root sourceRoot = packageRoots.get(PackageIdentifier.create(repositoryName, dir));
       if (sourceRoot != null) {
         return sourceRoot;
       }
@@ -350,7 +351,7 @@
   @Override
   public Artifact resolveSourceArtifact(PathFragment execPath,
       @SuppressWarnings("unused") RepositoryName repositoryName) {
-    return resolveSourceArtifactWithAncestor(execPath, null, null);
+    return resolveSourceArtifactWithAncestor(execPath, null, null, repositoryName);
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/actions/Root.java b/src/main/java/com/google/devtools/build/lib/actions/Root.java
index f39bced..59010e9 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Root.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Root.java
@@ -181,7 +181,7 @@
 
   @Override
   public int hashCode() {
-    return Objects.hash(execRoot, path.hashCode());
+    return Objects.hash(execRoot, path.hashCode(), isMainRepo);
   }
 
   @Override
@@ -193,7 +193,8 @@
       return false;
     }
     Root r = (Root) o;
-    return path.equals(r.path) && Objects.equals(execRoot, r.execRoot);
+    return path.equals(r.path) && Objects.equals(execRoot, r.execRoot)
+        && Objects.equals(isMainRepo, r.isMainRepo);
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java b/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
index ba48f7a..1e2e3d0 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
@@ -124,7 +124,7 @@
   }
 
   public PathFragment getPathUnderExecRoot() {
-    return getSourceRoot();
+    return repository.getPathUnderExecRoot().getRelative(pkgName);
   }
 
   /**