Rollback of commit 4b73e972d909bcd533f2f9940f95a00b9b73bdde.

*** Reason for rollback ***

Broke tests on CI: http://ci.bazel.io/job/bazel-tests/570/


*** Original change description ***

Roll forward execroot change

RELNOTES[INC]: Previously, an external repository would be symlinked into the
execution root at execroot/local_repo/external/remote_repo. This changes it to
be at execroot/remote_repo. This may break genrules/Skylark actions that
hardcode execution root paths. If this causes breakages for you, ensure that
genrules are using $(location :target) to access files and Skylark rules are
using http://bazel.io/docs/skylark/lib/File.html's path, dirname, etc.
functions. Cust...

--
PiperOrigin-RevId: 147833177
MOS_MIGRATED_REVID=147833177
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Package.java b/src/main/java/com/google/devtools/build/lib/packages/Package.java
index 609a5c3..45fa5ca 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Package.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Package.java
@@ -290,10 +290,9 @@
     this.filename = builder.getFilename();
     this.packageDirectory = filename.getParentDirectory();
 
-    this.sourceRoot = getSourceRoot(filename, packageIdentifier.getPackageFragment());
+    this.sourceRoot = getSourceRoot(filename, packageIdentifier.getSourceRoot());
     if ((sourceRoot == null
-        || !sourceRoot.getRelative(packageIdentifier.getPackageFragment())
-            .equals(packageDirectory))
+        || !sourceRoot.getRelative(packageIdentifier.getSourceRoot()).equals(packageDirectory))
         && !filename.getBaseName().equals("WORKSPACE")) {
       throw new IllegalArgumentException(
           "Invalid BUILD file name for package '" + packageIdentifier + "': " + filename);