dockerfile copy command should not execute when file is unchanged.
on occasion, the copy command executes even though the file is apparently unchanced.
- the output of:
Moby Menu > Diagnose & Feedbackon OSX
- a reproducible case if this is a bug, Dockerfiles FTW
- page URL if this is a docs issue or the name of a man page
- host distribution and version ( OSX 10.10.x, OSX 10.11.x, Windows, etc )
Diagnostic id - C72B6511-1232-4B96-9926-EA87494D869F
OS X 10.11.5
dockerfile - https://gist.github.com/mattkime/387acee42ac494910060f6f20eea86d9
Steps to reproduce the behavior
docker run it a few times. sometimes the images will cache properly, sometimes not.