Fix usages of PathFragment segments that will become inefficient.

An upcoming replacement to PathFragment will not have efficient segment semantics, causing code to become unnecessarily inefficient.

RELNOTES: None
PiperOrigin-RevId: 182553098
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 9469ddd..ac62a3a 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
@@ -86,10 +86,10 @@
     if (tofind.startsWith(Label.EXTERNAL_PATH_PREFIX)) {
       // TODO(ulfjack): Remove this when kchodorow@'s exec root rearrangement has been rolled out.
       RepositoryName repository = RepositoryName.create("@" + tofind.getSegment(1));
-      return PackageIdentifier.create(repository, tofind.subFragment(2, tofind.segmentCount()));
+      return PackageIdentifier.create(repository, tofind.subFragment(2));
     } else if (!tofind.normalize().isNormalized()) {
       RepositoryName repository = RepositoryName.create("@" + tofind.getSegment(1));
-      return PackageIdentifier.create(repository, tofind.subFragment(2, tofind.segmentCount()));
+      return PackageIdentifier.create(repository, tofind.subFragment(2));
     } else {
       return PackageIdentifier.createInMainRepo(tofind);
     }