config: complete entry during creation

Don't set entry data when we "get" an entry from the collection, add the
data to the entry before it's put into the collection. This keeps the
entry creation logic in a single place.

src/libgit2/config_file.c

@@ -359,8 +359,6 @@ static int config_file_get(git_config_backend *cfg, const char *key, git_config_
 		return error;
 	}
 
-	entry->free = config_file_entry_free;
-	entry->payload = entries;
 	*out = entry;
 
 	return 0;
@@ -805,6 +803,8 @@ static int read_on_variable(
 	entry->value = var_value ? git__strdup(var_value) : NULL;
 	entry->level = parse_data->level;
 	entry->include_depth = parse_data->depth;
+	entry->free = config_file_entry_free;
+	entry->payload = parse_data->entries;
 
 	if ((result = git_config_entries_append(parse_data->entries, entry)) < 0)
 		return result;