Consider adding a flag for ignoring fchmod errors in copy_file

[Lastique]

As described in #178, there are cases when fchmod consistently fails for a particular filesystem. This causes copy_file failure, although the file is successfully copied, though without setting the original access mode and permissions. It may be desirable to suppress the error from copy_file if fchmod fails.

One possible solution is to add a new flag in copy_options to ignore errors from fchmod.

Side note: It may be worthwhile to detect NFS with statfs (for it f_type should be NFS_SUPER_MAGIC) and only set S_IWUSR permission when the target file is on NFS. This way we may not have to change the target file permissions after copying. Although, if a filesystem does not support fchmod, it is possible that fstat/statx for the target file returns a different mode from the original file, which means we will try calling fchmod anyway.

[kkumar45]

@Lastique: Any update on it, when it will be planned?

[Lastique]

No updates, unfortunately. I haven't got around to it.

[kkumar45]

@Lastique Can you please consider it? Our customers are impacted due to this.