Possibly a bug

From: Jiergir Ogoerg <f35f22fan@gmail.com>
Date: Nov 17, 2013, 02:59 UTC
Message-ID: <CAJbVpmyoZCCQU3w8oMTJfxFr4f1cSNTgF+qQW6QD5e44LYg_Ug@mail.gmail.com>

Hi, As suggested by the git book/tutorial I cloned "simplegit-progit" to learn using git. The issue: git log --since=5.years yields 2 commits, while git log --since=6.years yields 3 commits, despite the "Date" in both cases being March 2008. Is it a bug?

Using Fedora 20 amd64 with git version 1.8.4.2

Details:
//==> FIVE YEARS
simplegit-progit$ git log --since=5.years
commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gmail.com>
Date:   Mon Mar 17 21:52:11 2008 -0700

    changed the verison number

commit 085bb3bcb608e1e8451d4b2432f8ecbe6306e7e7
Author: Scott Chacon <schacon@gmail.com>
Date:   Sat Mar 15 16:40:33 2008 -0700

    removed unnecessary test code
//<== FIVE YEARS

//==> SIX YEARS
simplegit-progit$ git log --since=6.years
commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gmail.com>
Date:   Mon Mar 17 21:52:11 2008 -0700

    changed the verison number

commit 085bb3bcb608e1e8451d4b2432f8ecbe6306e7e7
Author: Scott Chacon <schacon@gmail.com>
Date:   Sat Mar 15 16:40:33 2008 -0700

    removed unnecessary test code

commit a11bef06a3f659402fe7563abf99ad00de2209e6
Author: Scott Chacon <schacon@gmail.com>
Date:   Sat Mar 15 10:31:28 2008 -0700

    first commit
//<== SIX YEARS