minio storage iterator shows different behavior with local fs iterator.
in local fs storage:
``` go
s.IterateObjects("prefix", func(path,obj)
println(path) // show "prefix/xxx.file"
})
```
in minio storage:
```go
s.IterateObjects("prefix", func(path,obj)
println(path) // show "xxx.file"
})
```
I think local fs is correct, minio use wrong `basePath` to trim storage
path prefix.
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Co-authored-by: Giteabot <teabot@gitea.io>
