git-repo external and umask don't play nice

[hugoh]

Describe the bug

With umask = 0o077, a git-repo external refresh always believes that the destination copy has changed.

To reproduce

I have the following external defined:

[".vim/pack/chezmoi/start/chezmoi.vim"]
  type = "git-repo"
  url = "https://github.com/alker0/chezmoi.vim.git"
  refreshPeriod = "168h"
  clone.args = ["--depth", "1"]
  pull.args = ["--ff-only"]

With the following in the config:

umask = 0o077

cm apply -R .vim/pack/chezmoi/start/chezmoi.vim will always say: .vim/pack/chezmoi/start/chezmoi.vim has changed since chezmoi last wrote it?:

~ ❯ chezmoi apply -R .vim/pack/chezmoi/start/chezmoi.vim 
.vim/pack/chezmoi/start/chezmoi.vim has changed since chezmoi last wrote it? overwrite/all-overwrite/skip/quit

Overwriting and running it again will produce the same outcome again.

Removing the umask setting fixes the problem.

Expected behavior

~ ❯ chezmoi apply -R .vim/pack/chezmoi/start/chezmoi.vim 
Already up to date.

Output of command with the --verbose flag

Same.

[twpayne]

I'm unable to reproduce this.

What is the output of:

chezmoi apply --debug ~/.vim/pack/chezmoi/start/chezmoi.vim

and:

chezmoi managed | grep chezmoi