decomposePar: Removed inappropriate and fragile -ifRequired option

Resolves bug-report https://bugs.openfoam.org/view.php?id=3852

applications/utilities/parallelProcessing/decomposePar/decomposePar.C

@@ -66,14 +66,6 @@ Usage
         Remove any existing \a processor subdirectories before decomposing the
         geometry.
 
-      - \par -ifRequired \n
-        Only decompose the geometry if the number of domains has changed from a
-        previous decomposition. No \a processor subdirectories will be removed
-        unless the \a -force option is also specified. This option can be used
-        to avoid redundant geometry decomposition (eg, in scripts), but should
-        be used with caution when the underlying (serial) geometry or the
-        decomposition method etc. have been changed between decompositions.
-
       - \par -dict \<filename\>
         Specify alternative dictionary for the decomposition.
 
@@ -272,11 +264,6 @@ int main(int argc, char *argv[])
         "force",
         "remove existing processor*/ subdirs before decomposing the geometry"
     );
-    argList::addBoolOption
-    (
-        "ifRequired",
-        "only decompose geometry if the number of domains has changed"
-    );
 
     // Include explicit constant options, have zero from time range
     timeSelector::addOptions(true, false);
@@ -291,7 +278,6 @@ int main(int argc, char *argv[])
     bool decomposeGeomOnly       = args.optionFound("noFields");
     bool decomposeSets           = !args.optionFound("noSets");
     bool forceOverwrite          = args.optionFound("force");
-    bool ifRequiredDecomposition = args.optionFound("ifRequired");
 
     if (decomposeGeomOnly)
     {
@@ -420,13 +406,6 @@ int main(int argc, char *argv[])
                 << exit(FatalError);
         }
 
-        // Reuse the decomposition if permitted
-        if (ifRequiredDecomposition && nProcs == nDomains)
-        {
-            decomposeFieldsOnly = true;
-            Info<< "Using existing processor directories" << nl;
-        }
-
         // Get flag to determine whether or not to distribute uniform data
         const label distributeUniform =
             decomposeParDict.lookupOrDefault<bool>("distributed", false);