basename doesn't accept options in bash. This causes the VERSIONS variable get the 'N/A' value for $ nvm ls command.
From basename man page:
NAME
basename - strip directory and suffix from filenames
SYNOPSIS
basename NAME [SUFFIX]
basename OPTION
DESCRIPTION
Print NAME with any leading directory components removed. If specified, also remove a trailing SUFFIX.
--help display this help and exit
--version
output version information and exit
coreutils version used in Linux Mint 14 Nadia.
GNU coreutils 8.12.197-032bb September 2011 BASENAME(1)
No idea if this flag exists on FreeBSD or other unixes (if they use gnu coreutils shouldn't be any problem)
