set rand in DoExecute

Modules/Applications/AppClassification/app/otbSOMClassification.cxx

@@ -180,9 +180,6 @@ private:
 
   void DoUpdateParameters() override
   {
-    if (!HasUserValue("rand")) {
-      SetParameterInt("rand", std::time(0));
-    }
   }
 
   void DoExecute() override
@@ -253,6 +250,11 @@ private:
     itk::RandomPermutation randPerm(numberOfStreamDivisions);
     unsigned int           index = 0;
 
+    // Randomize seed if not given
+    if (!HasUserValue("rand")) {
+      SetParameterInt("rand", std::time(0));
+    }
+
     // reset seed and step once (itk::RandomPermutation may have used it)
     randomGen->SetSeed(GetParameterInt("rand"));
     randomGen->GetVariateWithClosedRange();