Document that Response.iter_lines is broken and should be avoided #6570
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This method is broken in a couple of significant ways: - If delimiter is None, and if one chunk happens to end with \r and the following chunk begins with \n, this method will yield a bogus blank line at that point. - If delimiter is a string, and if a chunk happens to end with that string, this method will yield a bogus blank line at that point. This is broken both with and without decode_unicode=True, and it is broken both with and without stream=True. (Setting stream=True makes the problem worse, because then the chunk boundaries are partially dependent on server or network I/O chunking.) Unless and until this behavior is fixed, this method should not be used.
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The
Response.iter_linesmethod is seriously broken (it inserts fake blank lines in unpredictable places.)The earliest report of this I've found is pull #2431 (January 2015).
The behavior was apparently fixed in the 3.0.0 branch, by pulls #3923 and #3984. (I think #3923 fixes the
delimiter!=Nonecase and #3984 fixes thedelimiter=Nonecase. But I haven't tested it.)The problem was raised again in issues #3980, #4121, and #5540.
Pull #4629 attempted to partially fix the issue in the master branch, and was rejected.
Personally, I am skeptical that there is any benefit in preserving this broken behavior. But folks who know better than I do have said that it needs to be maintained.
As long as this isn't fixed, people using the library should be informed that method is broken and they shouldn't use it.