Timestamp of files from Cache and Workspace are at time of unpacking

When I attach a workspace or restore a cache, the modified timestamp on the files in the directory I’m unpacking gets the timestamp from when the attach/restore step is performed.

My CI pipeline is for iOS, and the Xcode build system determines when to recompile files based on it’s modified timestamp. This forces a fresh/clean build on every commit and due to the size of the project that is building, the build times are very long.

If the modified timestamps can be preserved, this would enable incremental builds for iOS which would significantly reduce our build time (and I’m sure many others).

I’m hoping to be able to define a parameter or env var which would allow me to choose to preserve this timestamp. I know for tar this is possible with an optional parameter --atime-preserve[=METHOD]. Perhaps this is also possible for the caching mechanism CircleCI uses?

Is this a reasonable/feasible feature request?