python3.pkgs.rpy2: 2.9.5 -> 3.2.2

There have been significant changes, therefore it doesn't make sense
anymore to maintain the python2 and python3 version in the same file.
We'll be able to drop the python2 version soon, some time after we have
switched sage to python3.

pkgs/development/python-modules/rpy2/rpy2-3.x-r-libs-site.patch

@@ -0,0 +1,21 @@
+diff --git a/rpy2/rinterface_lib/embedded.py b/rpy2/rinterface_lib/embedded.py
+index cc32b6d..3969ad0 100644
+--- a/rpy2/rinterface_lib/embedded.py
++++ b/rpy2/rinterface_lib/embedded.py
+@@ -113,6 +113,16 @@ def _initr(interactive: bool = True,
+         if isinitialized():
+             return None
+         os.environ['R_HOME'] = openrlib.R_HOME
++
++        # path to libraries
++        existing = os.environ.get('R_LIBS_SITE')
++        if existing is not None:
++            prefix = existing + ':'
++        else:
++            prefix = ''
++        additional = '@NIX_R_LIBS_SITE@'
++        os.environ['R_LIBS_SITE'] = prefix + additional
++
+         options_c = [ffi.new('char[]', o.encode('ASCII')) for o in _options]
+         n_options = len(options_c)
+         n_options_c = ffi.cast('int', n_options)