Merge branch 'develop' into mplegendre-multi_pkgsrc_roots

Conflicts:
	lib/spack/spack/cmd/create.py
	lib/spack/spack/cmd/extensions.py
	lib/spack/spack/cmd/fetch.py
	lib/spack/spack/cmd/uninstall.py
	lib/spack/spack/config.py
	lib/spack/spack/database.py
	lib/spack/spack/directory_layout.py
	lib/spack/spack/packages.py
	lib/spack/spack/spec.py

var/spack/repos/builtin/packages/petsc/package.py

@@ -18,7 +18,7 @@ class Petsc(Package):
     depends_on("hypre")
     depends_on("parmetis")
     depends_on("metis")
-    depends_on("hdf5")
+    depends_on("hdf5+mpi")
     depends_on("mpi")
 
     def install(self, spec, prefix):