[BUG] dotbare finit -u URL checkout crashes if conflicted file is more than like 100 files

[kazhala]

The reason is that git only lists conflicted files up to a certain thresh hold and dotbare finit -u URL would read the input of dotbare checkout output. This makes in-place migration unstable if user have lots of dotfiles, potential fixes would be performing a "recursive" checkout process until git doesn't output any conflicted files.