Add a patch to disable mpi4py with an env. var.

This is similar to what was done in the previous merge for the
cdms2 package, but this time for the regrid2 package.

recipe/0005-env_flag_to_disable_mpi4py_in_regrid2.patch

@@ -0,0 +1,67 @@
+diff -ruN cdms-3.1.5/regrid2/Lib/esmf.py cdms-3.1.5-patch/regrid2/Lib/esmf.py
+--- cdms-3.1.5/regrid2/Lib/esmf.py 2020-07-31 03:01:33.000000000 +0200
++++ cdms-3.1.5-patch/regrid2/Lib/esmf.py 2021-06-09 15:18:29.043255491 +0200
+@@ -18,6 +18,9 @@
+ import ESMF
+ from functools import reduce
+
++from .util import getenv_bool
++
++
+ # constants
+ R8 = ESMF.TypeKind.R8
+ R4 = ESMF.TypeKind.R4
+@@ -463,7 +466,13 @@
+ # communicator
+ self.comm = None
+
++ mpi_disabled = getenv_bool("CDMS_NO_MPI", "False")
++
+ try:
++ # skip trying to load mpi4py module
++ if mpi_disabled:
++ raise Exception()
++
+ from mpi4py import MPI
+ self.comm = MPI.COMM_WORLD
+ except BaseException:
+diff -ruN cdms-3.1.5/regrid2/Lib/mvESMFRegrid.py cdms-3.1.5-patch/regrid2/Lib/mvESMFRegrid.py
+--- cdms-3.1.5/regrid2/Lib/mvESMFRegrid.py 2020-07-31 03:01:33.000000000 +0200
++++ cdms-3.1.5-patch/regrid2/Lib/mvESMFRegrid.py 2021-06-09 10:40:05.039237116 +0200
+@@ -22,9 +22,16 @@
+ except Exception:
+ os.environ['MPICH_INTERFACE_HOSTNAME'] = 'localhost'
+
++from .util import getenv_bool
++
+ ESMF.Manager(debug=False)
+ HAVE_MPI = False
++mpi_disabled = getenv_bool("CDMS_NO_MPI", "False")
++
+ try:
++ # skip trying to load mpi4py module
++ if mpi_disabled:
++ raise Exception()
+ from mpi4py import MPI
+ HAVE_MPI = True
+ except BaseException:
+diff -ruN cdms-3.1.5/regrid2/Lib/util.py cdms-3.1.5-patch/regrid2/Lib/util.py
+--- cdms-3.1.5/regrid2/Lib/util.py 1970-01-01 01:00:00.000000000 +0100
++++ cdms-3.1.5-patch/regrid2/Lib/util.py 2021-06-09 10:39:10.295311114 +0200
+@@ -0,0 +1,16 @@
++import os
++
++
++def getenv_bool(name, default=None):
++ valid_bool_str = ["true", "false"]
++ value = os.environ.get(name, default)
++
++ if value is None:
++ raise ValueError("{!r} was not set".format(name))
++
++ if value.lower() not in valid_bool_str:
++ raise ValueError(
++ "{!r} is not a valid value for {!r}, allowed values: {!r}".format(
++ value, name, valid_bool_str))
++
++ return value.lower() == "true"

recipe/meta.yaml

@@ -13,9 +13,10 @@ source:
  - 0002-fixes_building_extensions.patch
  - 0003-Removes-modifying-ncmode-with-NC_NETCDF4-flag.patch
  - 0004-fix_add_env_flag_to_disable_mpi4py.patch
+ - 0005-env_flag_to_disable_mpi4py_in_regrid2.patch
 
 build:
- number: 6
+ number: 7
  skip: True # [win] 
 
 requirements: