"bus error" occurs when plist contains @sample keyword with no arguments

[metalefty]

Hi, I found invalid plist leads poudiere testport to Child process pid=29775 terminated abnormally: Bus error.

Step to reproduce

1. Choose any port, for example, x11/xterm
2. Add @sample keyword to PLIST_FILES or pkg-plist with no arguments
3. Run poudriere build test
4. It should fail but no helpful messages shown

(snip)
=>> Checking for staging violations... done
=======================<phase: package        >============================                                            
===>  Building package for xterm-333
Child process pid=29775 terminated abnormally: Bus error
*** Error code 1

Stop.
make: stopped in /usr/ports/x11/xterm
build of x11/xterm | xterm-333 ended at Sun May  6 23:31:55 JST 2018                                                   
build time: 00:00:18
!!! build failure encountered !!!
[00:00:23] Error: Build failed in phase: package
[00:00:23] Cleaning up
[00:00:24] Unmounting file systems

In this case, of course make package should fail because @sample keyword requires an argument.

====> Compressing man pages (compress-man)
====> Running Q/A tests (stage-qa)
===>  Building package for xterm-333
pkg-static: Plist error, directory listed as a file: 

Expected behaviour

poudriere should fail with helpful text, shouldn't terminated abnormally

(snip)
=>> Checking for staging violations... done
=======================<phase: package        >============================                                            
===>  Building package for xterm-333
MESSAGES LIKE "Plist error, directory listed as a file: " SHOULD BE SHOWN HERE
*** Error code 1

Stop.
make: stopped in /usr/ports/x11/xterm
build of x11/xterm | xterm-333 ended at Sun May  6 23:31:55 JST 2018                                                   
build time: 00:00:18
!!! build failure encountered !!!

[metalefty]

Just in case, not only PLIST_FILES, same bus error occurs if pkg-plist contains @sample with no arguments.

[bapt]

This is not a poudriere bug, this is a pkg bug can you report the bug to pkg, please?

[metalefty]

Okay.