bug: split_batch does not handle externally supplied new_batch case

[toofun666]

@frappe.whitelist()
def split_batch(batch_no: str, item_code: str, warehouse: str, qty: float, new_batch_id: str | None = None):
"""Split the batch into a new batch"""
batch = frappe.get_doc(dict(doctype="Batch", item=item_code, batch_id=new_batch_id)).insert()

looks like the method may receive new_batch_id but it does not handle the case where it is fed beforehand. Please include necessary branching if the new batch to split into is provided by calling code

[mihir-kandoi]

Please describe the issue in detail with current behaviour and expected behaviour with screenshots or screen recordings if possible.

[toofun666]

I needed to override a class method for processing of the Purchase Receipt on_submit and split the batches created by the Purchase Receipt submission further as per the quantities entered in Purchase Receipt Items for each item that has batch control.
During this, I needed to print labels, so I needed the new batch numbers created at this split process.
Since it was a deferred commit operation, checking immediately the batches created at the database is not possible. (maybe that is why the split_batch method is returning batch.name batch being the new batch created for Outward stock entry.
I noticed the split_batch accepts a predetermined target batch, so I was planning to supply it but obviously it returned a batch already exists message breaking the process.
I guess the .insert() at the end of the line breaks this. Or you should control if the new_batch_id is existing or not.