Comment 2 for bug 1559650

StacktraceTop:
 ___vsnprintf_chk (s=0x0, maxlen=<optimized out>, flags=1, slen=<optimized out>, format=0x7f1fe54ccae5 "%s%s", args=args@entry=0x7f1fce502da8) at vsnprintf_chk.c:55
 ___snprintf_chk (s=<optimized out>, maxlen=<optimized out>, flags=flags@entry=1, slen=slen@entry=18446744073709551615, format=format@entry=0x7f1fe54ccae5 "%s%s") at snprintf_chk.c:34
 snprintf (__fmt=0x7f1fe54ccae5 "%s%s", __n=<optimized out>, __s=<optimized out>) at /usr/include/x86_64-linux-gnu/bits/stdio2.h:64
 XauFileName () at ../AuFileName.c:83
 XauGetBestAuthByAddr (family=256, address_length=5, address=0x7f1fce502f80 "phhug", number_length=4, number=0x7f1fce502f50 "1024", types_length=2, types=0x7f1fecc671a0 <authnames>, type_lengths=0x7f1fecc67198 <authnameslen>) at ../AuGetBest.c:74