Allow yast python modules to work via either python2 or python3

src/yast-core.i

@@ -1,4 +1,7 @@
 %module ycp
+%begin %{
+#define SWIG_PYTHON_2_UNICODE
+%}
 
 %feature("autodoc", "3");
 

src/yast.py

@@ -1,3 +1,4 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
 import ycpbuiltins
 from ycp import Symbol, List, String, Integer, Boolean, Float, Code, Map, Byteblock, Path, Void
 
@@ -135,7 +136,11 @@ def meta_func_creator(func, lowercase):
 def Term(*args):
     from ycp import Term as YCPTerm
     from ycp import pyval_to_ycp
-    name = args[0]
+    from six import binary_type, text_type, PY2
+    if PY2 and isinstance(args[0], text_type):
+        name = binary_type(args[0])
+    else:
+        name = args[0]
     l = None
     if len(args) > 1:
         l = List()
@@ -147,18 +152,25 @@ def Term(*args):
 
 def Opt(*args):
     from ycp import Term as YCPTerm
+    from six import binary_type, text_type, PY2
     l = List()
     for arg in args:
+        if PY2 and isinstance(arg, text_type):
+            arg = binary_type(arg)
         l.add(Symbol(arg))
     return YCPTerm("opt", l)
 
 # Id can take argument other than string
 def Id(arg, dont_force_sym = False):
     from ycp import pyval_to_ycp
     from ycp import Term as YCPTerm
+    from six import binary_type, text_type, PY2
     l = List()
-    if isinstance(arg, str) and not dont_force_sym:
-        l.add(Symbol(arg))
+    if isinstance(arg, text_type) and not dont_force_sym:
+        if PY2:
+            l.add(Symbol(binary_type(arg)))
+        else:
+            l.add(Symbol(arg))
     else:
         l.add(pyval_to_ycp(arg))
     return YCPTerm("id", l)

src/ycpbuiltins.py

@@ -1,3 +1,4 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
 from ycp import List, String, Integer, Boolean, Float, Value
 from ycp import Term as YCPTerm
 

src/ytypes.i

@@ -22,10 +22,14 @@ YCPValue pyval_to_ycp(PyObject *input)
         return YCPFloat(PyFloat_AsDouble(input));
     if (PyString_Check(input))
         return YCPString(PyString_AsString(input));
+    if (PyUnicode_Check(input)) {
 #if PY_MAJOR_VERSION >= 3
-    if (PyUnicode_Check(input))
         return YCPString(_PyUnicode_AsString(input));
+#else
+        PyObject* encoded = PyUnicode_Encode(PyUnicode_AsUnicode(input), PyUnicode_GetSize(input), "ascii", NULL);
+        return YCPString(PyBytes_AsString(encoded));
 #endif
+    }
     if (PyList_Check(input)) {
         auto size = PyList_Size(input);
         if (size > 0 && PyFunction_Check(PyList_GetItem(input, 0))) {