Preserve permissions when copying files

[zachmargolis]

Hi there,

We have some custom Ore templates that provide default executables, such as a default script/ci for running tests, and we would like the newly-created gems to have these files be executable as well.

Thanks!

cc @bascule

[ggilder]

:+1: this would be useful!

[postmodern]

Sorry for not noticing these PRs sooner! It appears mode: :preserve copies the all of the permission bits. I'm assuming we want to only preserve the executable bit?

[zachmargolis]

@postmodern thanks! I think preserving all the bits is totally acceptable, and the simplest change we could to get the desired result