mail dumps core after unterminated '

[frankster]

Enter a single quote at the /usr/bin/mail prompt, and the programme crashes:

? '
mu_wordsplit failed: missing closing quote
Segmentation fault (core dumped)

Ubuntu 16.04.2 LTS
mailutils 1:2.99.99-1ubuntu2

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: mailutils 1:2.99.99-1ubuntu2
ProcVersionSignature: Ubuntu 4.4.0-79.100-generic 4.4.67
Uname: Linux 4.4.0-79-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.6
Architecture: amd64
Date: Mon Jun 19 12:44:43 2017
InstallationDate: Installed on 2012-03-26 (1910 days ago)
InstallationMedia: Mythbuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
SourcePackage: mailutils
UpgradeStatus: Upgraded to xenial on 2016-07-27 (327 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Randy Bush (r-randy)]

upgraded ubuntu to 18.04
```
ran.psg.com:/home/randy> uname -a
Linux ran.psg.com 4.15.0-33-generic #36-Ubuntu SMP Wed Aug 15 16:00:05 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
```
/usr/bin/mail` no longer works. this is becoming painful.
```
ran.psg.com:/home/randy> /usr/bin/mail -s foux randy < /dev/null
mail: mu_wordsplit failed: missing closing quote
mail: Unknown command: PѸÜU
mail: mu_wordsplit failed: missing closing quote
Segmentation fault (core dumped)
```
this is after an `apt install --reinstall mailutils mailutils-common`
```
ran.psg.com:/home/randy> /usr/bin/mail --version
mail (GNU Mailutils) 3.4
```