patch: get correct package directory for a given package

fixes #4236
fixes #5002

When a package is defined in more than one repository,
RepoPath.dirname_for_package_name may return the path
to either definition. This sidesteps that ambiguity by 
accessing the module associated with the package definition.

1 files changed, 15 insertions, 3 deletions

diff --git a/lib/spack/spack/patch.py b/lib/spack/spack/patch.py
index 78bb15f41c..c970f4dfdc 100644
--- a/lib/spack/spack/patch.py
+++ b/lib/spack/spack/patch.py
@@ -23,16 +23,28 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 import os
+import os.path
+import inspect
 
 import spack
 import spack.error
-import spack.stage
 import spack.fetch_strategy as fs
-
+import spack.stage
 from llnl.util.filesystem import join_path
 from spack.util.executable import which
 
 
+def absolute_path_for_package(pkg):
+    """Returns the absolute path to the ``package.py`` file implementing
+    the recipe for the package passed as argument.
+
+    Args:
+        pkg: a valid package object
+    """
+    m = inspect.getmodule(pkg)
+    return os.path.abspath(m.__file__)
+
+
 class Patch(object):
     """Base class to describe a patch that needs to be applied to some
     expanded source code.
@@ -90,7 +102,7 @@ class FilePatch(Patch):
     def __init__(self, pkg, path_or_url, level):
         super(FilePatch, self).__init__(pkg, path_or_url, level)
 
-        pkg_dir = spack.repo.dirname_for_package_name(pkg.name)
+        pkg_dir = os.path.dirname(absolute_path_for_package(pkg))
         self.path = join_path(pkg_dir, path_or_url)
         if not os.path.isfile(self.path):
             raise NoSuchPatchFileError(pkg.name, self.path)