When Matz changed Time#to_s format in 2006, frac part of Time string is dropped because it is considered not useful.
[ruby-dev:29440]

But recently we encounters some troubles the comparison of Time objects whose frac parts are different.
https://twitter.com/__gfx__/status/1143056072422219776

For example a is original object and b is once stored in RDB (and dropped the frac part).
Or there're multiple time objects which are generated in a single HTTP request.
Of course they are different and assert_equal will be failed but inspect doesn't show the frac part.