As explained in
https://github.com/spf13/afero/pull/291#issuecomment-807324649, now that
`afero` supports `io/fs.FS`, it requires `go` >= `1.15.10`.
Rather than pinning to `1.15` and occasionally confusing users who are
on < `1.15.10`, I thought simplest to jump straight to `1.16`.
Especially given `1.18` was just released, the upstream `go` team no
longer even supports `1.16`.
The change to `go.sum` was the result of running `go mod tidy`.
github.com/pkg/sftp to v1.13.1 (this fixes a security vulnerability)
golang.org/x/crypto to v0.0.0-20211108221036-ceb1ce70b4fa
golang.org/x/text to v0.3.7
Before this commit, `CopyOnWriteFs` would return `syscall.EEXIST` in `Mkdir` and `MkdirAll` when a directory already exists.
The main problem with this is that `os.IsExist` returns `false` for that error on Windows.
These methods now return `os.ErrExist`, which is in line with how the other file systems behave.
Fixes#189
Graham Anderson