WIP pquot: always keep SCP_WEIGHTS immutable

This matters for HPC-GAP, where the collector is made read-only
once it is used in a

lib/pquot.gi

@@ -481,7 +481,7 @@ end );
 ##
 UpdateWeightInfo := function( qs )
     local   n,  nhwg,  ranks,  class,  last_in_cl,  avector,  cl,  wt,  
-            avc2,  g,  h;
+            avc2,  g,  h,  i;
 
     n     := GeneratorNumberOfQuotient(qs);
     nhwg  := qs!.numberOfHighestWeightGenerators;
@@ -502,8 +502,11 @@ UpdateWeightInfo := function( qs )
     class := class + 1;
     qs!.collector![SCP_CLASS] := class;
 
-    wt := qs!.collector![SCP_WEIGHTS];
-    wt{n+[1..nhwg]} := [1..nhwg] * 0 + class;
+    wt := ShallowCopy(qs!.collector![SCP_WEIGHTS]);
+    for i in [1..nhwg] do
+        wt[n+i] := class;
+    od;
+    qs!.collector![SCP_WEIGHTS] := MakeImmutable(wt);
 
     avc2 := [1..n]+0;
     for g in [1..n] do
@@ -1321,7 +1324,7 @@ end );
 InstallGlobalFunction( AbelianPQuotient,
 function( qs )
     local   G,  one,  n,  gens,  LTM,  trailers,  d,  
-            generators,  i,  r,  l;
+            generators,  i,  r,  l,  wt;
 
     # Setup some variables.
     G    := qs!.preimage;
@@ -1371,8 +1374,12 @@ function( qs )
 
     ##  Update the weight information
     qs!.collector![SCP_CLASS] := 1;
-    qs!.collector![SCP_WEIGHTS]{[1..qs!.numberOfGenerators]} := 
-      [1..qs!.numberOfGenerators] * 0 + 1;
+    wt := ShallowCopy(qs!.collector![SCP_WEIGHTS]);
+    for i in [1..qs!.numberOfGenerators] do
+        wt[i] := 1;
+    od;
+    qs!.collector![SCP_WEIGHTS] := MakeImmutable(wt);
+
 
 end );