core (constants): added EXIT_CONFLICT

sat/core/constants.py

@@ -386,6 +386,7 @@ class Const(object):
     EXIT_NOT_FOUND = 16  # an item required by a command was not found
     EXIT_DATA_ERROR = 17  # data needed for a command is invalid
     EXIT_MISSING_FEATURE = 18  # a needed plugin or feature is not available
+    EXIT_CONFLICT = 19  # an item already exists
     EXIT_USER_CANCELLED = 20  # user cancelled action
     EXIT_INTERNAL_ERROR = 111  # unexpected error
     EXIT_FILE_NOT_EXE = (