Hi, all.

There is a problem to use uniq! for an array with shifting operations.
It seems to be a bug.

options = [1, 1, 1]
options.shift
p options.uniq
p options.uniq! { |h| h }

The expected result is

[1]
[1]

But, the returned values are

[1]
nil

It should return "[1]" for the second.

The testing environments are
ruby :

$ ruby --version
ruby 2.0.0p353 (2013-11-22 revision 43784) [x86_64-darwin12.5.0]

jruby :

$ ruby --version
jruby 1.7.10 (1.9.3p392) 2014-01-09 c4ecd6b on Java HotSpot(TM) 64-Bit Server VM 1.6.0_65-b14-462-11M4609 [darwin-x86_64]

and the referenced document is from
http://www.ruby-doc.org/core-2.1.0/Array.html#method-i-uniq

Returns nil if no changes are made (that is, no duplicates are found).