schema api sometimes fails to replace-field-type

When updating a schema via POST to  /solr/COLLECTION/schema using  replace-field-type , the call fails if the schema has existing copy-fields whose destination references a non-dynamic field of the  field-type which is being updated.

 
Example steps: # on a blank schema, add a field type and copy-field by POSTing

{
"add-field-type": [
{
"name": "spellcheck", "class": "solr.TextField","positionIncrementGap": "100",
"analyzer": {
"tokenizer":

{ "class": "solr.StandardTokenizerFactory" }

}
}
],
"add-field": [

{ "name": "spellcheck", "type": "spellcheck", "multiValued": true, "indexed": true, "stored": true }

],
"add-copy-field": [

{ "source": "important_data_s", "dest": "spellcheck" }

]
}
2. Later, send an update for the field type
{
"replace-field-type": [
{
"name": "spellcheck", "class": "solr.TextField","positionIncrementGap": "100",
"analyzer": {
"tokenizer":

{ "class": "solr.StandardTokenizerFactory" }

}
}
]
}
This results in "errorMessages":["Source or Destination SchemaField can't be NULL.\n"]}],}}The error does not trigger if, as mentioned above, the destination of the existing copy-field is dynamic OR if the source field mapping contains a wildcard e.g. {{*foo_s (edited)