Two tests in test_inspect.py failed for me with the following traceback:

======================================================================
FAIL: test_stack (__main__.TestInterpreterStack)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test/test_inspect.py", line 92, in test_stack
    (modfile, 16, 'eggs', ['    st = inspect.stack()\n'], 0))
AssertionError: ('/tmp/install//lib/python2.6/test/inspect_fodder.py', 16, 'eggs', ['    st = inspect.stack()\n'], 0) != ('/tmp/install/lib/python2.6/test/inspect_fodder.py', 16, 'eggs', ['    st = inspect.stack()\n'], 0)

This happened because I configured Python with "./configure --prefix=/tmp/install/" and autoconf automagically created paths such as ${prefix}/lib so it got a double slash. 

Double slashes are completely harmless on Unix and test_inspect.py is probably wrong in comparing two paths like that. Nevertheless, they are ugly and I think it is worthwhile to eliminate them. So here is patch that does that by adding a "hack" to configure.in.

Does this work if the prefix is "/"?

It does. Autoconf sees that prefix is the empty string "", but as the variable is defined it does not replace it with the default /usr/local. So it should be safe. Although it would be nice if someone else could test it too.

I think I'd rather fix the tests, using something like os.path.normpath().

Yes, that could be fixed too. But all tracebacks originating from the standard library also get the double slash:

>>> import fnmatch
>>> fnmatch.filter(1, 2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/bjourne/install//lib/python2.6/fnmatch.py", line 46, in filter
    res = translate(pat)
  File "/home/bjourne/install//lib/python2.6/fnmatch.py", line 78, in translate
    i, n = 0, len(pat)
TypeError: object of type 'int' has no len()

IMHO, that is ugly enough that it ought to be fixed.

Sounds good to me. How about you, Georg?

I'd still specialcase prefix == "/". Currently, with your patch it ends up as
sys.prefix == "", which is bad if someone does

x = os.path.join(sys.prefix, "lib", ...)

I think who configures with --prefix=/ can live with the double slashes.

Ok, I'll add a specialcase for that which should be trivial. Also, the manual for sys.prefix is a little vague and probably needs an update. 

File Added: fix-prefix-with-trailing-slash-problem-2.patch

New patch fixes your concern Georg.

Okay, thanks.
Martin, you know how to do the configure magic properly, do you want to commit this?

I think the problem with this patch is that % substitution is not widely available in /bin/sh. For example, on Solaris 9, /bin/sh gives 'bad substitution'. Even /usr/xpg4/bin/sh rejects it. So I think this should be redone using, say, sed.

Here is patch with sed instead. I hope this should be safe because all variants of UNIX should have sed I think.
File Added: fix-prefix-with-trailing-slash-problem-3.patch

Changed a bit (seems that backslash before the $ in the regex isn't
necessary) and checked in in r70903.