compgen -C Appends Extra Empty String Arguments

[Charles R. Harwood]

On Precise 12.04

When compgen is used to call an external command via -C, it adds three extra empty string arguments. While some commands are ok with that, it breaks many others.

==============================
Simple Test Case:

$ cat > /tmp/print_args <<EOF
#!/usr/bin/env python
import sys
print >>sys.stderr, sys.argv
EOF

$ chmod +x /tmp/print_args

# Without compgen
$ /tmp/print_args
['/tmp/print_args']

# With compgen
$ compgen -C '/tmp/print_args'
['/tmp/print_args', '', '', '']

==============================
Note that this was found remotely without access to a browser. From ubuntu-bug:
ProblemType: Bug
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
Date: Mon Dec 30 17:39:08 2013
Dependencies:
 base-files 6.5ubuntu6.6
 bash 4.2-2ubuntu2.1
 coreutils 8.13-3ubuntu3.2
 dash 0.5.7-2ubuntu2
 debconf 1.5.42ubuntu1
 debianutils 4.2.1ubuntu2
 dpkg 1.16.1.2ubuntu7.2
 gcc-4.6-base 4.6.3-1ubuntu5
 libacl1 2.2.51-5ubuntu1
 libattr1 1:2.4.46-5ubuntu1
 libbz2-1.0 1.0.6-1
 libc-bin 2.15-0ubuntu10.5
 libc6 2.15-0ubuntu10.5
 libgcc1 1:4.6.3-1ubuntu5
 liblzma5 5.1.1alpha+20110809-3
 libselinux1 2.1.0-4.1ubuntu1
 libtinfo5 5.9-4
 multiarch-support 2.15-0ubuntu10.5
 perl-base 5.14.2-6ubuntu2.3
 sensible-utils 0.0.6ubuntu2
 tar 1.26-4ubuntu1
 tzdata 2013g-0ubuntu0.12.04
 xz-utils 5.1.1alpha+20110809-3
 zlib1g 1:1.2.3.4.dfsg-3ubuntu4
DistroRelease: Ubuntu 12.04
InstallationMedia: Kubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
MarkForUpload: True
NonfreeKernelModules: fglrx
Package: bash-completion 1:1.3-1ubuntu8.1
PackageArchitecture: all
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 3.2.0-57.87-generic 3.2.52
SourcePackage: bash-completion
Tags: precise
Uname: Linux 3.2.0-57-generic x86_64
UpgradeStatus: Upgraded to precise on 2012-04-30 (609 days ago)