Import the Sources

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We need to find a suitable location in history from which to begin our repository. We definitely want pre-Drupal Kernel and the PSR-0 namespacing, but at the same time we'd like at least a reasonable start on CMI. It looks like from the history of the repository, there was quite a bit of overlap between CMI and at least PSR-0.

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Here's a list of significant commit hashes giving a rough timeline:

de356c1311802181b20f24aaba0ac688c4f0e6be - Aug 7, 2013: Most current D7 commit.
5b0715d78b4e26e86166ef4793a1ebf738e1d05c - May 31, 2012: Last commit before Drupal kernel
79f43572fcec3122c65a90d1f5a34fbd42f0cd5a - Mar 8, 2013: Creation of core/lib/Drupal/Core/Utility directory (first PSR-0 conversion other than Cache, DBTNG, and CMI)
44963050b20866f13c5168481657fbd7ec7e7ea3 - Mar 2, 2012: Merge of CMI into 8.x
bdb71c6fa79227d54a6ca6538af9212f20f09035 - Feb 29, 2012: Merge of DBTNGTNG into 8.x
1de1df57173cd9c1f1b4f99d6d11d6fc56ae8711 - Feb 11, 2012: Last commit on CMI branch before converting to PSR-0
037faa8fbf8cedc925b7477a8b1218e15ea0c50e - Jan 31, 2012: Issue #1400748 by Crell, jbrown, plach: Proposal for unified namespace organization. (still only contained cache conversion)
cfab9bc488b48f785e265199b5ca527988958f1b - Jan 29, 2012: Last commit before initial merge of the WSCCI branch
2451f7fc231ac8d8bab63b9bd04289a4954971ff - Jan 13, 2012: Issue #1323120 by pounard, aspilicious, beejeebus: Convert cache system to PSR-0. 
86ce7f97d54415ae8bfa55f273ea4be7697d6448 - Jan 13, 2012: Issue #1290658 Introduction of PSR-0 autoloader

So it looks like somewhere between Jan 13 and May 31, 2012 is where things started converting heavily to PSR-0. By May with the introduction of the Drupal Kernel, a large number of systems has already been converted: Language, Lock, Mail, Queue, StreamWrapper, Updater, Utility, Graph, Archiver, and others. So I think we'll need to back further than just the introduction of the Kernel itself.

The first systems converted were Cache, CMI, and then DBTNG (in that order). A semi-working of CMI appears to have existed before it was converted to PSR-0 in Feb 2012, but then it was fully converted before the main version was pulled into core Mar 2, 2012.

After March 8, a large number of systems are converted to PSR-0 in a short amount of time. My guess is that after that date, we won't be able to import changes wholesale, so some time in late Feb/early March looks like it's about the best time for starting the repository.

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Initially when I tried this, I used http://drupalcode.org/sandbox/damiankloip/1778654.git/commit/da3a59b, the last commit (March 8, 2012), before PSR-0 started converting in earnest. However that was after CMI, DBTNG, and the cache layers had already been converted. The reverting of DBTNG's PSR-0 version moved a large amount of files and was stretched over multiple commits. So instead of starting there, I went back another week to Feb 29, 2012, to the last commit before DBTNG's PSR-0 conversion d1aee00aaf7623616f791af8b64e14f39d74e372. The full log looks something like this:

git clone ../drupal8-git .
git checkout d1aee00aaf7623616f791af8b64e14f39d74e372

git branch 1.x
git checkout 1.x
git branch -D 8.x


# Revert PSR-0 restructuring.
git revert 037faa8fbf8cedc925b7477a8b1218e15ea0c50e

# Revert Cache conversion.
git revert 2451f7fc231ac8d8bab63b9bd04289a4954971ff

# Revert PSR-0 autoloader.
git revert 86ce7f97d54415ae8bfa55f273ea4be7697d6448

# Remove Symfony 2 (done manually because the /core directory move prevents Git
# from being able to undo commit c85d62c60902086e39fdea3ac5daa7f29f92edeb).
git apply remove_symfony-1178246.patch
git add core
git commit -m "Issue #1: Removing Symfony."

Removing Symfony also had to be done manually, as the /core directory move made using git revert impossible (afaik). Fortunately because Symfony wasn't actually used for a long time (about a month) after it's initial commit, rolling back it's change individually isn't difficult at all (as can be seen in 740963a).

To avoid versioning conflicts in the future, I've prepended "drupal-" to all the old version tags. As in the summary of commands above, I also restarted versioning back at a 1.x branch for this project.

As an added bonus, merging in the Pre-PSR-0 version of CMI is a piece of cake with this earlier version. After the success of being able to install and run Backdrop normally, I've pushed up this initial commit to the repo!

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Initially fixed with backdrop/backdrop@740963a.

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It's worth noting that I then had to revert the CMI branch. That's now being tracked in #2