sandboxing crash while writing stats
With 19556 fixed, Tor now crashes while trying to write stats.
(Sandbox) Caught a bad syscall attempt (syscall open)
/usr/bin/tor(+0x150566)[0x7f5547fe3566]
/lib/x86_64-linux-gnu/libpthread.so.0(open64+0x2d)[0x7f55466611ed]
/lib/x86_64-linux-gnu/libpthread.so.0(open64+0x2d)[0x7f55466611ed]
/usr/bin/tor(tor_open_cloexec+0x40)[0x7f5547fcb410]
/usr/bin/tor(start_writing_to_file+0xf2)[0x7f5547fdd0f2]
/usr/bin/tor(+0x14a25b)[0x7f5547fdd25b]
/usr/bin/tor(+0x14a3a8)[0x7f5547fdd3a8]
/usr/bin/tor(write_to_data_subdir+0x4f)[0x7f5547f711ef]
/usr/bin/tor(rep_hist_hs_stats_write+0x185)[0x7f5547f0b5b5]
/usr/bin/tor(+0x3e318)[0x7f5547ed1318]
/usr/bin/tor(+0x576e0)[0x7f5547eea6e0]
/usr/lib/x86_64-linux-gnu/libevent-2.0.so.5(event_base_loop+0x7fc)[0x7f554751c3dc]
/usr/bin/tor(do_main_loop+0x274)[0x7f5547ed4ad4]
/usr/bin/tor(tor_main+0x1b45)[0x7f5547ed81e5]
/usr/bin/tor(main+0x19)[0x7f5547ed05c9]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7f55460c4b45]
/usr/bin/tor(+0x3d619)[0x7f5547ed0619]