Problem with tokenize module and indents

[Tim]

I ran into a problem with a script i was playing with to check code 
indents and need some direction.  It seems to depend on if tabsize is 
set to 4 in editor and spaces and tabs indents are mixed on consecutive 
lines.  Works fine when editors tabsize was 8 regardless if indents are 
mixed.

Below are how the 3 test files are laid out, the sample code and output 
I get. 
Any help on how to detect this correctly would be appreciated.


# nano -T4 tabspacing_4.py
class Test:
    """triple quote"""              #indent is 1 tab
    def __init__(self, msg):    #indent is 4 spaces               << 
this gets reported as a dedent when there is no change in indent level
        self.msg = msg            #indent is 2 tabs

#nano -T8 tabspacing_8A.py
class Test:
        """triple quote"""              #indent is 1 tab
        def __init__(self, msg):    #indent is 8 spaces            << no 
indent change reported
            self.msg = msg            #indent is 1 tab + 4 spaces

#nano -T8 tabspacing_8B.py
class Test:
        """triple quote"""              #indent is 1 tab
        def __init__(self, msg):    #indent is 1 tab                  << 
no indent change reported
            self.msg = msg            #indent is 1 tab + 4 spaces



My script

#!/usr/bin/env python

import tokenize
from sys import argv

indent_lvl = 0
line_number = 0
lines = file(argv[1]).readlines()
done = False

def parse():

    def feed():

        global line_number, lines

        if line_number < len(lines):
            txt = lines[line_number]
            line_number += 1
        else:
            txt = ''

        return txt

    def indents(type, token, start, end, line):

        global indent_lvl, done

        if type == tokenize.DEDENT:
            indent_lvl -= 1
        elif type == tokenize.INDENT:
            indent_lvl += 1
        elif type == tokenize.ENDMARKER:
            done = True
            return
        else:
            return

        print "token=%s, line_number=%i, indent_lvl=%i" % 
(tokenize.tok_name[type], start[0], indent_lvl), line.strip()

    while not done:
        tokenize.tokenize(feed, indents)

parse()


$ ./sample.py tabspacing_4.py      
token=INDENT, line_number=3, indent_lvl=1 """triple quote"""          
#indent is 1 tab
token=DEDENT, line_number=4, indent_lvl=0 def __init__(self, msg):    
#indent is 4 spaces      <-- PROBLEM HERE
token=INDENT, line_number=5, indent_lvl=1 self.msg = msg          
#indent is 2 tabs
token=DEDENT, line_number=8, indent_lvl=0

$ ./sample.py tabspacing_8A.py 
token=INDENT, line_number=3, indent_lvl=1 """triple quote"""          
#indent is 1 tab
token=INDENT, line_number=5, indent_lvl=2 self.msg = msg          
#indent is 1 tab + 4 spaces
token=DEDENT, line_number=8, indent_lvl=1
token=DEDENT, line_number=8, indent_lvl=0

$ ./sample.py tabspacing_8B.py 
token=INDENT, line_number=3, indent_lvl=1 """triple quote"""          
#indent is 1 tab
token=INDENT, line_number=5, indent_lvl=2 self.msg = msg          
#indent is 1 tab + 4 spaces
token=DEDENT, line_number=8, indent_lvl=1
token=DEDENT, line_number=8, indent_lvl=0