Is EPC + concurrent only on 24.4+?

[MatthewRalston]

Currently running Emacs 24.3.1, trying to install jedi => epc => concurrent => deferred.

EPC (20140609.2234 in MELPA) lists concurrent as a direct dependency.
Concurrent (0.3.1 => 20161228.1930) lists 'emacs-24.3' and deferred (0.5.0) as dependencies.
Deferred (0.5.0 => 20170901.630) lists 'emacs-24.4' as a dependency, which is not satisfied by. Does this imply that the minimum version of emacs epc is usable with is 24.4 implicitly? It seems strange for concurrent to be compatible with different versions than it's own dependency.