[ python-Bugs-979794 ] diffutil errors when comparing 2 0 byte entries

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Bugs item #979794, was opened at 2004-06-25 08:12
Message generated for change (Comment added) made by bcannon
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Category: Python Library
Group: Python 2.3
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Robert M. Zigweid (rzigweid)
Assigned to: Barry A. Warsaw (bwarsaw)
Summary: diffutil errors when comparing 2 0 byte entries

Initial Comment:
difflib has a problem where if the two things that it is comparing are 
0 byte/null that when it comes time to output the results, it errors 
because a generator appears to not be properly set up.

To duplicate easily, use the diff.py utility in Tools/scripts and diff 
two zero byte files. 

This error does not occur if either of the objects being compared has 
content.


  File "diff.py", line 40, in ?
    sys.stdout.writelines(diff)
  File "/usr/local/lib/python2.3/difflib.py", line 1215, in context_diff
    for group in 
SequenceMatcher(None,a,b).get_grouped_opcodes(n):
  File "/usr/local/lib/python2.3/difflib.py", line 574, in 
get_grouped_opcodes
    if codes[0][0] == 'equal':
IndexError: list index out of range


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>Comment By: Brett Cannon (bcannon)
Date: 2004-07-10 16:55

Message:
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Fixed in rev. 1.21 in CVS.  Not backporting in case someone actually 
relies on this behavior.

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Comment By: Barry A. Warsaw (bwarsaw)
Date: 2004-06-25 20:17

Message:
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user_id=12800

Probably a dup of 980117


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