This is totally crazy:

"With our extremely linear history, the first commit in a repo hash a hash that starts with 0000000, the second commit is 0000001, the third is 0000002, and so on!"
[...]
"There is no way to easily create content with the desired prefix (that would prevent the whole point of checksums). So we only have one option: testing many combinations of junk data until we can find one that passes our criteria."