[Python] Is it possible to nest transactions in peewee + sqlite?

Executing the code below produces unexpected results. Is it a problem with peewee, sqlite, or my understanding of transactions?

The code creates a transaction, then calls 3 times a function that creates 3 records in its own transaction. The function succeeds the 1st and 3rd time, but it fails the 2nd.

I would expect to find 6 records in the database, 3 created at the 1st call and 3 created at the 3rd, and the records created during the 2nd call would be rolled back.

Instead I find only the records created at the 3rd call.

import peewee

class DbTest(peewee.Model):
test = peewee.CharField()
class Meta:
database = db

def test(txt):
with db.transaction():
DbTest.create(test=txt + '1')
DbTest.create(test=txt + '2')
if txt == 'b':
raise
DbTest.create(test=txt + '3')

DbTest().drop_table(True)
DbTest().create_table(True)

with db.transaction():
for txt in ['a', 'b', 'c']:
try:
test(txt)
except:
pass

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