Fix T44135: Sapling add-on broken in 2.74rc3.

Nothing broken here actually, just missing info (shape needs at least three levels
of branching to take effect).

To be backported to 2.74.

add_curve_sapling/__init__.py

@@ -253,7 +253,7 @@ class AddTree(bpy.types.Operator):
         description='Branch upward attraction',
         default=0.0, update=update_tree)
     shape = EnumProperty(name='Shape',
-        description='The overall shape of the tree (Shape)',
+        description='The overall shape of the tree (Shape) - WARNING: at least three "Levels" of branching are needed',
         items=shapeList,
         default='7', update=update_tree)
     baseSize = FloatProperty(name='Base Size',
@@ -415,7 +415,9 @@ class AddTree(bpy.types.Operator):
             row.prop(self, 'resU')
 
             box.prop(self, 'handleType')
-            box.prop(self, 'shape')
+            sub = box.row()
+            sub.active = self.levels >= 3
+            sub.prop(self, 'shape')
             box.prop(self, 'seed')
             box.prop(self, 'ratio')
 

add_curve_sapling/utils.py

@@ -594,7 +594,9 @@ def fabricate_stems(addsplinetobone, addstem, baseSize, branches, childP, cu, cu
             else:
                 childStems = leaves * shapeRatio(leafDist, p.offset / p.lengthPar)
         elif n == 1:
-            # If this is the first level of branching then upward attraction has no effect and a special formula is used to find branch length and the number of child stems
+            # If this is the first level of branching then upward attraction has no effect
+            # and a special formula is used to find branch length and the number of child stems.
+            # This is also here that the shape is used.
             vertAtt = 0.0
             lMax = length[1] + uniform(-lengthV[1], lengthV[1])
             lMax += copysign(1e-6, lMax)  # Move away from zero to avoid div by zero