Funny story: my first task when I joined the original iPhone team was to merge our forked WebKit with master. It was a sort of hazing ritual slash "when else would we do it but when someone new joins?". Anyways, we used a tool called SVK[1] in order to get very primitive "git-like" abilities. It was basically a bunch of scripts that used SVN under the hood. For example, in order to get the "local everything"-style behaviors of git, the very first thing it did was checkout every single version of the repository in question. For WebKit, this meant that the first day was spent leaving the computer alone and letting it download for hours. I made the mistake of having a space somewhere in the path of the target folder, which broke something or other, so I ended up having to do it all over again.
Anyways, I distinctly remember one of the instructions for merging WebKit in our internal wiki being something like "now type `svk merge`, but hit ctrl-c immediately after! You don't want to use the built-in merge, it'll break everything, but this is the only way to get a magic number that you can find stored in [some file] after the merge has started. If it's not there, try `svk merge` again and let it go a little longer than last time." A few hires later (I think possibly a year after) someone set up a git mirror internally to avoid having to do this craziness, which if I remember correctly, was treated with some skepticism. This was 2007, so why would we try some new-fangled git thing when we had svk?
Anyways, I distinctly remember one of the instructions for merging WebKit in our internal wiki being something like "now type `svk merge`, but hit ctrl-c immediately after! You don't want to use the built-in merge, it'll break everything, but this is the only way to get a magic number that you can find stored in [some file] after the merge has started. If it's not there, try `svk merge` again and let it go a little longer than last time." A few hires later (I think possibly a year after) someone set up a git mirror internally to avoid having to do this craziness, which if I remember correctly, was treated with some skepticism. This was 2007, so why would we try some new-fangled git thing when we had svk?
1. https://wiki.c2.com/?SvkVersionControl