Draft: fix isClosed bug in offsets.py

Use built-in isClosed() function instead of isReallyClosed which is buggy.

src/Mod/Draft/draftgeoutils/offsets.py

@@ -33,7 +33,6 @@ import DraftVecUtils
 
 from draftgeoutils.general import geomType, vec
 from draftgeoutils.geometry import get_normal
-from draftgeoutils.wires import isReallyClosed
 from draftgeoutils.intersections import wiresIntersect, connect
 
 # Delay import of module until first use because it is heavy
@@ -238,7 +237,7 @@ def offsetWire(wire, dvec, bind=False, occ=False,
         if norm is None:
             norm = App.Vector(0, 0, 1)
 
-    closed = isReallyClosed(wire)
+    closed = wire.isClosed()
     nedges = []
     if occ:
         length = abs(dvec.Length)