cvs.reader improperly prematurely ends row parsing when parsing a row with an escaped newline but with quoting turned off.  cvs.reader properly handles quoted newlines.  cvs.writer properly handles writing escaped unquoted newlines so only the reader has an issue.

Given a dialect with escapechar='\\', quoting=csv.QUOTE_NONE, lineterminator='\n':

writer.writerow(['one\nelement']) will correctly write 'one\\\nelement\n'

however pass that back into a reader and it will produce two rows: ['one\n'] ['element']

I would expect the reader to parse it correctly and return the original value of ['one\nelement']
 
I've attached a test script that exhibits the improper behavior.  It uses a dialect to set an escapechar and disable quoting.

I've confirmed that bug in the latest repo version, still exists. I attach patch for py3k. 
I'll try to have a look at it in the current version, as soon as it will be fixed I'll port it to 2.7.

CSV is not well defined format. What you expect to read from csv.reader(['one', 'two'])? If two rows ['one'] and ['two'], than the reader in its own right and there is no bug which can be fixed.

Serhiy,  sorry I'm not sure I understand your question.  But if you take a look at the script that exhibits the problem I think the bug that I'm reporting becomes more clear.

Namely, using the dialect configuration shown in the script, the round trip conversion from string through writer then through the reader back to string is inconsistent.  The reader should return as output the same input that was given to the corresponding writer and this is not the case.  

So even if CVS in not well defined I believe the writer and reader should at least be consistent.

On input, the reader sees a line like 

    ['one\\\n','element']

from the file iterator and successfully escapes the newline character, but still interprets the end of the string as the end of a record.  I've attached a patch that modifies this behavior, so that encountering the end of a string immediately after an escaped \r or \n is does not begin a new record.

New changeset 940748853712 by R David Murray in branch 'default':
#15927: Fix cvs.reader parsing of escaped \r\n with quoting off.
http://hg.python.org/cpython/rev/940748853712

Although this is clearly a bug fix, it also represents a behavior change that could cause a working program to fail.  I have therefore only applied it to 3.4, but I'm open to arguments that it should be backported.

Thanks for the patch, Michael.