bazel cmdline: break 'PackageIdentifier extends SkylarkValue'

The edge was spuriously added in CL 161526182 so that the value could
be printed by BasePrinter, but that doesn't seem to matter to any test.

PiperOrigin-RevId: 277416405
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 4db5bf6..e4f285d 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
@@ -20,8 +20,6 @@
 import com.google.common.collect.Interner;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
-import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.io.Serializable;
 import java.util.Objects;
@@ -36,8 +34,7 @@
  */
 @AutoCodec
 @Immutable
-public final class PackageIdentifier
-    implements Comparable<PackageIdentifier>, Serializable, SkylarkValue {
+public final class PackageIdentifier implements Comparable<PackageIdentifier>, Serializable {
   private static final Interner<PackageIdentifier> INTERNER = BlazeInterners.newWeakInterner();
 
   public static PackageIdentifier create(String repository, PathFragment pkgName)
@@ -235,9 +232,4 @@
         .compare(pkgName, that.pkgName)
         .result();
   }
-
-  @Override
-  public void repr(SkylarkPrinter printer) {
-    printer.repr(toString());
-  }
 }