I see the same with version 1.20_01, so it's nothing new.

$ perl -MTime::Piece -E 'say Time::Piece->strptime("2015-04-28T19:40:0
+0", q{%Y-%m-%dT%T})->strftime;'
Tue, 28 Apr 2015 19:40:00 UTC
$ perl -MTime::Piece -E 'say Time::Piece->strptime("2015-04-28T19:40:0
+0", q{%FT%T})->strftime;'
Error parsing time at /usr/lib64/perl5/Time/Piece.pm line 469.
[download]

If you avoid %F for now that should serve as a workaround.