Comment # 9 on bug 1040589 from Martin Li��ka

So I did analysis of 2 packages before the changes in Factory happened:

1) gzip - as mentioned a temp file was used and zipped. Temp file name probably
causes the divergence as it's always different.

2) sed - it uses pthreads (but not passed as CFLAGS), thus I added
-fprofile-update=atomic to cflags. See documentation here:

https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html

and I've got it, diff in between 2 runs:

./gnulib-tests/nanosleep.gcda: a3000000:  37:PROGRAM_SUMMARY
checksum=0x99d0fa93
[snip]
./gnulib-tests/nanosleep.gcda:  01a10000:  14:COUNTERS arcs 7 counts
./gnulib-tests/nanosleep.gcda:        0 2 1 1 0 1 29 30

./gnulib-tests/nanosleep.gcda: a3000000:  37:PROGRAM_SUMMARY
checksum=0xc3046d04
[snip]
./gnulib-tests/nanosleep.gcda:        0 2 1 1 0 1 30 31

./lib/stat-time.h:

stat_time_normalize (int result, struct stat *st _GL_UNUSED)
{
#if defined __sun && defined STAT_TIMESPEC
  if (result == 0)
    {
      long int timespec_resolution = 1000000000;
      short int const ts_off[] = { offsetof (struct stat, st_atim),
                                   offsetof (struct stat, st_mtim),
                                   offsetof (struct stat, st_ctim) };
      int i;
      for (i = 0; i < sizeof ts_off / sizeof *ts_off; i++)
        {
          struct timespec *ts = (struct timespec *) ((char *) st + ts_off[i]);
          long int q = ts->tv_nsec / timespec_resolution;
          long int r = ts->tv_nsec % timespec_resolution;
          if (r < 0)
            {
              r += timespec_resolution;
              q--;
            }
          ts->tv_nsec = r;
          /* Overflow is possible, as Solaris 11 stat can yield
             tv_sec == TYPE_MINIMUM (time_t) && tv_nsec == -1000000000.
             INT_ADD_WRAPV is OK, since time_t is signed on Solaris.  */
          if (INT_ADD_WRAPV (q, ts->tv_sec, &ts->tv_sec))
            {
              errno = EOVERFLOW;
              return -1;
            }
        }
    }
#endif
  return result;
}

It loops based on how fast time flies. This can't be stable.