[issue45126] [sqlite3] cleanup and harden connection init

[Erlend E. Aasland]

Erlend E. Aasland <erlend.aasland at innova.no> added the comment:

I modified your second example slightly:

```
import sqlite3

conn = sqlite3.connect(":memory:")
conn.text_factory=bytes
conn.row_factory = sqlite3.Row
cursor = conn.execute("CREATE TABLE foo (bar)")
numbers = range(4)
cursor.executemany("INSERT INTO foo (bar) VALUES (?)", ((str(v),) for v in numbers))
cursor.execute("SELECT bar FROM foo")

print("first fetch")
for row in cursor.fetchmany(2):
    print(type(row[0]))

conn.__init__(":memory:")
conn.execute("CREATE TABLE foo (bar)")
letters = "a", "b", "c", "d"
conn.executemany("INSERT INTO foo (bar) VALUES (?)", ((v,) for v in letters))

# Currently this uses the old database, old row_factory, but new text_factory"
print("second fetch")
for row in cursor.fetchall():
    print(type(row[0]))
```

Here's the output:
first fetch
<class 'bytes'>
<class 'bytes'>
second fetch
<class 'str'>
<class 'str'>

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue45126>
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