The following code demonstrates the problem succinctly:

###
import inspect,sys

print 'Version info:',sys.version_info
print

f1 = inspect.getabsfile(inspect)
f2 = inspect.getabsfile(inspect.iscode)
print 'File for `inspect`       :',f1
print 'File for `inspect.iscode`:',f2
print 'Do these match?',f1==f2
if f1==f2:
    print 'OK'
else:
    print 'BUG - this is a bug in this version of Python'

###  EOF

Running this on my system (Linux, Ubuntu Edgy) with 2.3, 2.4 and 2.5 produces:

tlon[bin]> ./python2.3 ~/code/python/inspect_bug.py
Version info: (2, 3, 6, 'final', 0)

File for `inspect`       : /home/fperez/tmp/local/lib/python2.3/inspect.py
File for `inspect.iscode`: /home/fperez/tmp/local/lib/python2.3/inspect.py
Do these match? True
OK
tlon[bin]> python2.4 ~/code/python/inspect_bug.py
Version info: (2, 4, 4, 'candidate', 1)

File for `inspect`       : /usr/lib/python2.4/inspect.py
File for `inspect.iscode`: /home/fperez/tmp/local/bin/inspect.py
Do these match? False
BUG - this is a bug in this version of Python
tlon[bin]> python2.5 ~/code/python/inspect_bug.py
Version info: (2, 5, 0, 'final', 0)

File for `inspect`       : /usr/lib/python2.5/inspect.py
File for `inspect.iscode`: /home/fperez/tmp/local/bin/inspect.py
Do these match? False
BUG - this is a bug in this version of Python


###

The problem arises in the fact that inspect relies, for functions (at least), on the func_code.co_filename attribute to contain a complete path.  This changed between 2.3 and 2.4, but the inspect module was never updated.  This code:

###
import inspect,sys

print 'Python version info:',sys.version_info
print 'File info for `inspect.iscode function`:'
print ' ',inspect.iscode.func_code.co_filename
print
### EOF

shows the problem:

tlon[bin]> ./python2.3 ~/code/python/inspect_bug_details.py
Python version info: (2, 3, 6, 'final', 0)
File info for `inspect.iscode function`:
  /home/fperez/tmp/local//lib/python2.3/inspect.py

tlon[bin]> python2.5 ~/code/python/inspect_bug_details.py
Python version info: (2, 5, 0, 'final', 0)
File info for `inspect.iscode function`:
  inspect.py

###

(2.4 has the same issue).

Basically, if the func_code.co_filename attribute now stores only the final filename without the full path, then the logic in the inspect module needs to be changed to accomodate this so that correct paths are reported to the user like they were in the 2.3 days.