Simple sleep scripts causes SEGFAULT

[Alex Coffin]

I couldn't get bashbug to send this, so I manually am emailing it.
"/usr/bin/bashbug: rmail: not found"
Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu'
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL
-DHAVE_CONFIG_H   -I.  -I../. -I.././include -I.././lib  -Wdate-time
-D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector-strong -Wformat
-Werror=format-security -Wall
uname output: Linux minmus 4.4.0-97-generic #120-Ubuntu SMP Tue Sep 19
17:28:18 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.3
Patch Level: 48
Release Status: release

Description:
    Segmentation fault. I'm honestly not sure why. I was using batsh to
make a simple script. When I ran it generated a segfault. The segmentation
fault DOES NOT occur if "sleep" is replaced with "echo".
    I also ran it on "GNU bash, version 4.4.12(1)-release
(x86_64-redhat-linux-gnu)" using codingground (
https://www.tutorialspoint.com/execute_bash_online.php) the same issue
occurred.

Repeat-By:
    Run the following script (assuming you trust me lol):
    function sleep {
      local dur
      dur="$1"
      # if replaced with "echo" no segfault.
      sleep ${dur}s
    }
    "sleep" $((5))