Unexpected behavior from sprintf()

I stumbled across this by accident from this StackOverflow question:

http://stackoverflow.com/q/10300325/324364

and a subsequent discussion in the StackOverflow R chat room:

http://chat.stackoverflow.com/transcript/message/3431991#3431991

The issue is the output from the following code:

sprintf('%05s',as.character(1:5))

It appears that when this is run in OS X in either 2.14.2 or 2.15.0, the
output is:

[1] "00001" "00002" "00003" "00004" "00005"

whereas when it is run on other platforms (I saw examples from various
Windows versions and one user on Ubuntu, all using 2.15.0 I believe) you
get:

[1] "    1" "    2" "    3" "    4" "    5"

There was some uncertainty as to which behavior is "expected". Does anyone
have any insight into which behavior is "correct" and whether this is a bug
or not?

- Joran

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