luParser sectionHandler update wrong body

[zhixzhan]

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Describe the bug

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1. have a QnA file include model info options:

> !# @source.urls = https://download

<a id = "1"></a>

# ? who is the ceo?

'''
Sorry, I don't know.
'''

2. insert an empty section works fine

> !# @source.urls = https://download


# ?
'''

'''
<a id = "1"></a>

# ? who is the ceo?

'''
Sorry, I don't know.
'''

3. updated this section with

# ? how
'''

'''

result turn out to be:

> !# @source.urls = https://download


# ? how
'''

'''
'''  // unexpected insert
<a id = "1"></a>

# ? who is the ceo?

'''
Sorry, I don't know.
'''

and in parse result Body also not correct.

To Reproduce

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1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior

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Screenshots

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Additional context

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[bug]

[zhixzhan]

when qna file do not include model info section in header (options), won't re-produce this bug.