Some globstar patterns produce duplicate entries and a null filename

[Ulf Magnusson]

GNU bash, version 4.2.24(1)-release (i686-pc-linux-gnu)

Take the following example, assumed to be run in an empty directory:

$ mkdir a
$ echo **
a
$ echo **/**
 a a
$ echo **/**/**
 a a a

I would expect the result to be just 'a' in all cases.

You also get back a null filename, as shown by

$ for f in **/**/**; do echo "'$f'"; done
''
'a'
'a'
'a'

/Ulf