libpython: encoding is now passed to Popen parameters (#1914)

Fixes #1521

python/grass/script/core.py

@@ -92,6 +92,7 @@ _popen_args = [
     "universal_newlines",
     "startupinfo",
     "creationflags",
+    "encoding",
 ]
 
 
@@ -464,11 +465,6 @@ def start_command(
 
     :return: Popen object
     """
-    if "encoding" in kwargs.keys():
-        # This variable was never used for anything.
-        # See https://github.com/OSGeo/grass/issues/1521
-        encoding = kwargs.pop("encoding")  # noqa: F841
-
     options = {}
     popts = {}
     for opt, val in kwargs.items():