Description of problem:
Starting with coreutils 5.2.0-4, /bin/chown does not allow simple
dotted user.group notation as previous versions did. It seems that
only the colon user:group notation is allowed:

# /bin/chown rpm.rpm /tmp/whatever
/bin/chown: `rpm.rpm': invalid user

Also, when upgrading the rpm package, a similar error is shown as it
seems the post script invokes /bin/chown rpm.rpm on some files.

Version-Release number of selected component (if applicable):
5.2.0-4

How reproducible:
Always

Steps to Reproduce:
1. Upgrade to coreutils-5.2.0-4
  
Actual results:
/bin/chown doesn't allow for user.group dotted notation.

Expected results:
/bin/chown should allow for user.group dotted notation as previous
versions did.

Additional info: