Add a small post about git-merge stages

_posts/2016-10-04-git-merge-stages.md

@@ -0,0 +1,65 @@
+---
+layout:    post
+title:     "git-merge stages"
+date:      2016-10-04 12:46:00
+tags:      [git]
+published: true
+author:
+    name: Gergely Polonkai
+    email: gergely@polonkai.eu
+---
+
+This was a mail to my company’s internal Git mailing list, after I
+realised many colleagues can’t wrap their heads around merge
+conflicts.
+
+>Hello all,
+>
+>I just saw this on
+>the [git-users](https://groups.google.com/forum/#!forum/git-users)
+>list and thought it could help you when you bump into a merge
+>conflict. It is an excerpt from a mail by Konstantin Khomoutov (one
+>of the main contributors on the list), with a few modifications of
+>mine. Happy debugging :)
+>
+>>When a merge conflict is detected for a file, Git:
+>>
+>>1. Updates the entry for that file in the index to make it contain
+>>   several so-called “stages”:
+>>  * `0`: “Ours” version – that one which was there in this index entry
+>>    before we begun to merge. At the beginning of the conflict, like
+>>    right after the `git merge` or `git rebase` command this won’t
+>>    exist (unless you had the file in the index, which you didn’t, did
+>>    you?). When you resolve the conflict and use `git add
+>>    my/conflicting/file.cc`, this will be the version added to the
+>>    staging area (index), thus, the resolution of the conflict.
+>>  * `1`: The version from the common ancestor commit, ie. the version
+>>    of the file both of you modified.
+>>  * `2`: The version from `HEAD`. During a merge, this is the current
+>>    branch. During a rebase, this is the branch or commit you are
+>>    rebasing onto, which usually will be `origin/develop`).
+>>  * `3`: The version being merged, or the commit you are rebasing.
+>>2. Updates the file in the work tree to contain conflict markers and
+>>   the conflicting chunks of text between them (and the text from the
+>>   common ancestor if the `diff3` style of conflict markers was set).
+>>
+>>Now you can use the numbers in point 1 to access the different stages
+>>of the conflicting file. For example, to see the common ancestor (the
+>>version both of you modified), use
+>>
+>>```
+>>git show :1:my/conflicting/file.cc
+>>```
+>>
+>>Or, to see the difference between the two conflicting versions, try
+>>
+>>```
+>>git diff :2:my/conflicting/file.cc :3:my/conflicting/file.cc
+>>```
+>>
+>>**Note** that you can’t use the `:0:` stage *before* you stage your
+>>resolution with `git add`, and you can’t use the `:2:` and `:3:`
+>>stages *after* you staged the resolution.
+>>
+>>Fun fact: behind the scenes, these are the files (*revisions*) `git mergetool`
+>>accesses when it presents you the conflict visually.

css/style.sass

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 .tag-label:hover:after
   box-shadow: inset 0 1px 1px $menu-background
+
+blockquote
+  font-size: 100%