The reference manual documentation for raw string literals says

"""Note also that a single backslash followed by a newline is
interpreted as those two characters as part of the string, *not* as a line
continuation."""

This is not the observed behavior.

>>> s = """ABC\
... 123"""
>>> s
'ABC123'
>>> 

Line continuations are ignored by triple quoted strings.



In addition, the reference manual documentation for "\x" escapes says

| ``\xhh``        | Character with hex value *hh*   | (4,5) |

where footnote (4) stays

   Unlike in Standard C, at most two hex digits are accepted.

However, the implementation requires exactly two hex digits:

>>> "\x41"
'A'
>>> "\x4."
ValueError: invalid \x escape
>>> "\x4" 
ValueError: invalid \x escape
>>>

Your example does not use a "raw" string -- a raw string has an 'r' in 
front of the opening string quotes.  Try this instead:

>>> s = r"""a\
... b"""
>>> s
'a\\\nb'

Your second issue is correct -- the definition of \xXX in Python has 
changed over the years to what you observed.  I still don't think it 
matches the C standard though. :-)

Assigning to Georg for a doc fixup.  I'm assuming this is also for 
higher Python versions.

Fixed in r60193, r60194 (2.5).