dd: should return 1 when stderr is redirected to /dev/full but returns 101

[jfinkels]

GNU dd v9.4.113-c01ee:

$ : | dd 2> /dev/full; echo $?
1

uutils dd:

$ : | ./target/debug/dd 2> /dev/full; echo $?
101

This test case appears in GNU test suite file tests/dd/stderr.sh.