[chef] knife error

[David Montgomery < >]

Hi,

In an automated python  script under runit supervision, I am getting
this error and I have no idea what it means.  The only knife command I
am using via a os.system call is knife client delete mynode --yes

Any ideas?  running the command manually from the command line works.

/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:51:in
`join': can't convert nil into String (TypeError)
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:51:in
`site_subcommands'
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:74:in
`subcommand_files'
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:37:in
`load_commands'
        from /usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife.rb:112:in
`load_commands'
        from /usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife.rb:160:in
`run'
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/application/knife.rb:128:in
`run'
        from /usr/lib/ruby/gems/1.8/gems/chef-0.10.8/bin/knife:25
        from /usr/bin/knife:19:in `load'
        from /usr/bin/knife:19
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:51:in
`join': can't convert nil into String (TypeError)
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:51:in
`site_subcommands'
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:74:in
`subcommand_files'
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife/core/subcommand_loader.rb:37:in
`load_commands'
        from /usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife.rb:112:in
`load_commands'
        from /usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/knife.rb:160:in
`run'
        from 
/usr/lib/ruby/gems/1.8/gems/chef-0.10.8/lib/chef/application/knife.rb:128:in
`run'
        from /usr/lib/ruby/gems/1.8/gems/chef-0.10.8/bin/knife:25
        from /usr/bin/knife:19:in `load'
        from /usr/bin/knife:19