Support Python 2 for a bit more

But the end is coming!

mpcdf_common.py

@@ -58,14 +58,19 @@ def check_for_update():
     else:
         setattr(sys.modules["mpcdf_common"], "checked_for_updates", 1)
 
+    if (sys.version_info > (3, 0)):
+        set_encoding = {"encoding" : "utf-8"}
+    else:
+        set_encoding = {}
+
     plugin_dir = os.path.dirname(os.path.realpath(__file__))
     git_dir = os.path.join(plugin_dir, ".git")
-    local_rev = check_output(["git", "--git-dir", git_dir, "rev-parse", "HEAD"], encoding="utf-8").strip()
+    local_rev = check_output(["git", "--git-dir", git_dir, "rev-parse", "HEAD"], **set_encoding).strip()
 
     url = "https://gitlab.mpcdf.mpg.de/mpcdf/osc-plugins.git"
 
     def update_server_rev():
-        server_rev, _ = check_output(["git", "ls-remote", url, "master"], encoding="utf-8").split(maxsplit=1)
+        server_rev, _ = check_output(["git", "ls-remote", url, "master"], **set_encoding).split(maxsplit=1)
         with open(rev_file, "w") as fd:
             fd.write(server_rev)