platforms (e.g., Cygwin) that are "particular" about open files, this will
cause other regression tests that use the same temp file to fail:

    $ ./python.exe -E -tt Lib/test/regrtest.py -l
    test_largefile test_mmap test_mutants
    test_largefile
    test test_largefile failed -- got -1794967295L, but expected 2500000001L
    test_mmap
    test test_mmap crashed -- exceptions.IOError: [Errno 13] Permission denied: '@test'
    test_mutants
    test test_mutants crashed -- exceptions.IOError: [Errno 13] Permission denied: '@test'

This patch solves the problem by adding missing "try/finally" blocks. Note
that the "large" size of this patch is due to many white space changes --
otherwise, the patch is small.

I tested this patch under Red Hat Linux 8.0 too.