[Bug 2505515] nss_sss: getpwnam results in a -1 fd being passed to fstat

https://bugzilla.redhat.com/show_bug.cgi?id=2505515

--- Comment #6 from Florian Weimer  ---
There is no conditional check in glibc. You must have looked at the wrong
sources (sorry, it's complicated due to the sysdeps overrides).

(gdb) disassemble fstat
Dump of assembler code for function __GI___fstat64:
   0x00000000000e4620 <+0>:     endbr64
   0x00000000000e4624 <+4>:     mov    $0x5,%eax
   0x00000000000e4629 <+9>:     syscall
   0x00000000000e462b <+11>:    cmp    $0xfffffffffffff000,%rax
   0x00000000000e4631 <+17>:    ja     0xe4638 <__GI___fstat64+24>
   0x00000000000e4633 <+19>:    ret
   0x00000000000e4634 <+20>:    nopl   0x0(%rax)
   0x00000000000e4638 <+24>:    mov    0x1047a1(%rip),%rdx        # 0x1e8de0
   0x00000000000e463f <+31>:    neg    %eax
   0x00000000000e4641 <+33>:    mov    %eax,%fs:(%rdx)
   0x00000000000e4644 <+36>:    mov    $0xffffffff,%eax
   0x00000000000e4649 <+41>:    ret
End of assembler dump.