From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.6 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 620641F51C for ; Sat, 19 May 2018 03:07:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752059AbeESDHs (ORCPT ); Fri, 18 May 2018 23:07:48 -0400 Received: from mail-ua0-f177.google.com ([209.85.217.177]:44413 "EHLO mail-ua0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751117AbeESDHr (ORCPT ); Fri, 18 May 2018 23:07:47 -0400 Received: by mail-ua0-f177.google.com with SMTP id h15-v6so6624989uan.11 for ; Fri, 18 May 2018 20:07:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=o9rBj/HSB6D6XPiExpk0qZQxEiZIK7X9FwchHgUpLGQ=; b=mEcucma7v+nbM7vq6VDhAMVGsEaQR9EbTf5fLHr5maizjfogrePALRl4+f/2CPpfT4 X9TLwyQ34jOuJb2dsUhlSTpVvdHqXk9PqysVZRvIfQCmXRXJvstwBuEUJjvbSS4Jte9V LQYW9VVmn/BKGYjtPXeQYRQ6Dw/vkQIXt2WmThdiZN68JmVdIt+xequLeycPuMlCCDhg nuha+W4TaTP+iXphvi5xUiuTEE4M3alMxzcJnGhIQ3bGtIsHErcj0yQdh6AeoU3B+ncU 9JK5qpW07//qQJgGRUpKnUZ+ZuqfYe4yWS6QteyilgIK57FAdAL1WsI6FoXM4oIADReE MFyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=o9rBj/HSB6D6XPiExpk0qZQxEiZIK7X9FwchHgUpLGQ=; b=jCTC2gEEGRs7T5nC/FISaKcvXD6er+/FP4Nt1FEga2SQJid4gGJC8a2gtbfwVanf92 L2txTDUOnG7CiNia3wU/sFc798c6HE7cPkRcVe/Yq87vRPerVrdmd/WqRzt290RCYbLx CEEsXCf4aa+kupLbbTzT+Xr0TIm4YZZ04J+8JW3uhhkSs4omOB/dDIpx9D13PtS67ZcD WORkdb0gU8hKJkwPEK15wigtHIEBDEL0vpkr8xM7QOwsCS15yabtdvsaISUwbqpCWDpw 2JmWZGN4VOC+pasL3L46PiJ0/SkU3f4L3wZEbuoXo2GOAmkOJwGtiSzggA+oQ+99eiiG FljA== X-Gm-Message-State: ALKqPwc9V686q/rkHqD6wkYXzFQC74ukQ41GPPy5YAV62LAaL6YnoGO5 riMpCyPtAdzehZDiK+X4QAA7uEMgAAZ8OLN2oSqLsg== X-Google-Smtp-Source: AB8JxZpovtnj/su//rbu7ncaJafGIcNanOV6nCQ7xLngp3vZjSbPS2OuksAfNOg/g/+jAC9SD7kWZ+gKehszWk1o368= X-Received: by 2002:ab0:a1a:: with SMTP id q26-v6mr9234970uah.23.1526699266360; Fri, 18 May 2018 20:07:46 -0700 (PDT) MIME-Version: 1.0 Received: by 10.176.95.4 with HTTP; Fri, 18 May 2018 20:07:45 -0700 (PDT) From: Elijah Newren Date: Fri, 18 May 2018 20:07:45 -0700 Message-ID: Subject: Fun puzzle: successful merge's contents depends on...commit timestamps? To: Git Mailing List Content-Type: text/plain; charset="UTF-8" Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Check this out; I merge another branch successfully: $ git merge -m F $othersha; echo $? 0 This is just a simple test repo: $ git log --oneline 18f5e65 (HEAD -> master) F 7472b46 E ea0d801 D 4486f96 C 7727e3b B ee47c13 A Below it is important to note that one commit was made at 1526194997, and this value doesn't appear anywhere else in fast-export output: $ git fast-export --no-data master | grep 1526194997 author Elijah Newren 1526194997 -0700 committer Elijah Newren 1526194997 -0700 Let's create a new branch and rewrite history ONLY changing that one timestamp: $ git checkout -b redo $ git fast-export --no-data redo | \ sed -e s/1526194997/1500000000/ | \ git fast-import --quiet --force At this point, the trees for 'master' and 'redo' match, as you'd expect: $ git diff --quiet master HEAD; echo $? 0 Let's redo that merge, shall we?: $ git checkout --quiet 'redo^1' $ git merge -m newF 'redo^2'; echo $? $ 0 Did we get the same merge result? Nope: $ git diff --quiet master HEAD; echo $? 1 I believe there are about half a dozen solutions to this puzzle. Can you find at least one?