[PATCH] Add commit message guidelines to developer policy

[hfinkel at anl.gov]

REPOSITORY
  rL LLVM

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Comment at: docs/DeveloperPolicy.rst:283
@@ +282,3 @@
+guidelines that will help review, search in logs, email formatting and so on.
+Mostly, the rules that apply are similar to other git repositories, such as:
+
----------------
Good commit messages help in reconstructing the rationale for the state of the code, that's their most important purpose.

Saying 'git repositories' is a bit confusing, since we still primarily use svn. Maybe say 'giv/svn'?

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Comment at: docs/DeveloperPolicy.rst:294
@@ +293,3 @@
+* The body should be aligned to 80 columns and have as many paragraphs as
+  necessary, but not more than that. Meaning you should be concise, but
+  explanatory, including a complete reasoning, but leaving examples, code
----------------
Please don't say this. IMHO, we don't have a problem with commit messages being too long; and small code examples explaining what the commit is addressing can be really informative after the fact. We could say that, if the commit message is long, to please provide a summary paragraph at the top.


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Comment at: docs/DeveloperPolicy.rst:300
@@ +299,3 @@
+  the body, as simple as "Patch by John Doe.". This is how we officially
+  handle attribution, and there are automated processes that use that, so
+  please keep this pattern.
----------------
use that -> rely on this format

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Comment at: docs/DeveloperPolicy.rst:306
@@ +305,3 @@
+
+While these rules match most of the cases, we're aware that some cases are not
+covered, and that's why we don't think reverting patches with "bad" commit
----------------
I'd remove this paragraph. I don't think we should commit to this. ;)

http://reviews.llvm.org/D8197

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