MSO conditional comments truncate table content in 3.10.1

[amureki]

Hey there!
We discovered a regression in the new version of the library (3.10.1):
HTML content after MS Office conditional comments is truncated when inside a <table> element.

Reproduction

import markdown

html = """
<table>
<!--[if mso]>-->
<td>keep</td>
<!--<![endif]-->
<td>also keep</td>
</table>
"""

markdown.markdown(html)

Expected:

<table>
<!--[if mso]>-->
<td>keep</td>
<!--<![endif]-->
<td>also keep</td>
</table>

Actual:

<table>
</table>

Context

These are standard MS Office/Outlook conditional comments used in HTML emails for Outlook compatibility.

Regression

Works in 3.10, broken in 3.10.1.
I think, it was introduced in f925349

[amureki]

I created a PR with a regression test in #1591

[waylan]

This appears to only be an issue inside <table> for some reason. Although, to be fair, I didn't try every possible tag so it might occur in some other scenarios.

>>> src = '''
... <div>
... <!--[if mso]>-->
... <div>bar</div>
... <!--<!endif]-->
... <div>baz</div>
... </div>
... '''
>>> markdown.markdown(src)
'<div>\n<!--[if mso]>-->\n<div>bar</div>\n<!--<!endif]-->\n<div>baz</div>\n</div>'
>>> src = '''
... <table>
... <!--[if mso]>-->
... <td>foo</td>
... <!--<!endif]-->
... <td>bar</td>
... </table>
... '''
>>> markdown.markdown(src)
'<table>\n</table>'

[facelessuser]

😢 These cases are getting a bit exhausting. At least, since it is table-specific, it is likely to be easier to get to the bottom.

[facelessuser]

3rd, 4th, or 5th time's a charm (lost count) 🤞🏻. PR in #1592.

[facelessuser]

@waylan, don't release anything. I want to dig more into this.

[facelessuser]

I think I have some more fixes coming.