#7372: fix regression in pstats: a previous fix to handle cProfile data in add_callers broke handling of profile data.

#9428: fix running scripts from profile/cProfile with their own name and the right namespace.  Same fix as for trace.py in #1690103.

Revert r83395, it introduces test failures and is not necessary anyway since we now have to nul-terminate the string anyway.

reads on a BZ2File object, rather than returning incorrect results.

where 'id -G' and posix.getgroups() returned the same information,
but one of the sources contains duplicate information. Rewrite the
check using sets instead of lists.