Replace /home/$USER/trunk with /mnt/host/source/ in reinterpret_path_in_chroot.

BUG=chromium:282431
TEST=Ran image_to_live with sudo

Change-Id: Iac0c5942c13935b9efd5e267c070b3bcec95c4c6
Reviewed-on: https://chromium-review.googlesource.com/167669
Tested-by: Chris Sosa <sosa@chromium.org>
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Chris Sosa <sosa@chromium.org>
diff --git a/common.sh b/common.sh
index c2cc517..6cc92f2 100644
--- a/common.sh
+++ b/common.sh
@@ -987,7 +987,7 @@
       fi
 
       # Prepend the chroot repository path.
-      echo "/home/${USER}/trunk/${relative_path}"
+      echo "/mnt/host/source/${relative_path}"
     fi
   else
     # Path is already inside the chroot :).