Change alteration merge to remove all found duplicates

Before it terminated too quickly so it would incloude half of the
duplicates.
This would cause a problem if we added multiple bits with the same
ident (nested record values for example).

server/pkg/dal/alteration.go

@@ -96,10 +96,12 @@ func (aa AlterationSet) Merge(bb AlterationSet) (cc AlterationSet) {
 			}
 
 			if a.compare(*aux[j]) {
+				if !found {
+					cc = append(cc, aux[j])
+				}
+
 				seen[j] = true
 				found = true
-				cc = append(cc, aux[j])
-				break
 			}
 		}
 

server/pkg/dal/alteration_test.go

@@ -89,6 +89,14 @@ func TestMerge(t *testing.T) {
 						},
 					},
 				},
+				&Alteration{
+					AttributeAdd: &AttributeAdd{
+						Attr: &Attribute{
+							Ident: "foo",
+							Type:  &TypeJSON{Nullable: false},
+						},
+					},
+				},
 			},
 			cc: AlterationSet{
 				&Alteration{