Strange behavior for os:cmd()

[Sergey Yelin]

Hi there,

Just found os:cmd() gives differend results when I try to execute
external program by name and by full path. For example,

1>os:cmd("hg").
"Mercurial Distributed SCM\n\nbasic commands:\n\n add
...
[SKIP OTHER MERCURIAL HELP OUTPUT]
"
2>  os:find_executable("hg").
"c:/Program Files (x86)/TortoiseHg/hg.exe"
3> os:cmd(os:find_executable("hg")).
[]
4> os:cmd("c:/Program Files (x86)/TortoiseHg/hg.exe").
[]

Is this correct behavior or am I missing something?