always read files using utf-8 encoding

(cherry picked from commit 1f4f4626cee075e108337ab0ae641181ab81b272)
test utf-8 encoding in copy from

(the test would fail sometimes due to the charset
randomization if the FileReader wasn't using utf-8
explicitly)

(cherry picked from commit 4d6beda442d848ba1f4f22efb7fb8ff2a5dd6aae)