A minor change in the path of ijars: previously the exec path of a java_binary was a prefix of the exec path of the associated ijar, which may cause problems.

This was discovered using my "bindir == genfilesdir == outputdir" experiment.

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MOS_MIGRATED_REVID=89285440

src/main/java/com/google/devtools/build/lib/rules/java/BaseJavaCompilationHelper.java

diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/BaseJavaCompilationHelper.java b/src/main/java/com/google/devtools/build/lib/rules/java/BaseJavaCompilationHelper.java
index 3f8448a..f0b4bde 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/BaseJavaCompilationHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/BaseJavaCompilationHelper.java
@@ -136,8 +136,7 @@
 
   private Artifact getIjarArtifact(Artifact jar, boolean addPrefix) {
     if (addPrefix) {
-      PathFragment ruleBase = ruleContext.getLabel().getPackageIdentifier().getPathFragment()
-              .getRelative(ruleContext.getLabel().getName()).getRelative("_ijars");
+      PathFragment ruleBase = ruleContext.getUniqueDirectory("_ijar");
       PathFragment artifactDirFragment = jar.getRootRelativePath().getParentDirectory();
       String ijarBasename = FileSystemUtils.removeExtension(jar.getFilename()) + "-ijar.jar";
       return getAnalysisEnvironment().getDerivedArtifact(