Fix regression in salt.utils.copyfile()

In pull request #9599, I added code to make salt.utils.copyfile() set
the ownership and permissions of the new file to those of the
pre-existing file. However, this raises an exception when the
destination file doesn't exist, which happens on file.managed states
which are creating new files.

This commit fixes that regression.
Merge pull request #9615 from terminalmage/issue9527

Fix regression in salt.utils.copyfile()