Canonicalize parent path in ReadTrustedStep.isDescendant in case JENKINS_HOME is a symlink

Author: dwnusbaum

src/main/java/org/jenkinsci/plugins/workflow/multibranch/ReadTrustedStep.java

@@ -248,7 +248,7 @@ private static boolean isDescendant(FilePath child, FilePath parent) throws IOEx
             if (child.isRemote() || parent.isRemote()) {
                 throw new IllegalStateException();
             }
-            return new File(child.getRemote()).getCanonicalFile().toPath().startsWith(parent.absolutize().getRemote());
+            return new File(child.getRemote()).getCanonicalFile().toPath().startsWith(new File(parent.getRemote()).getCanonicalPath());
         }
 
         private static final long serialVersionUID = 1L;