spares: clarify some test about merging copies
This new output clarify the important part out this merging : we want to be able to record the copy source even it is outside of the sparse profile.
#require black test-repo
Black needs the real USERPROFILE in order to run on Windows
#if msys
$ USERPROFILE="$REALUSERPROFILE"
$ export USERPROFILE
#endif
$ cd $RUNTESTDIR/..
$ black --check --diff `hg files 'set:(**.py + grep("^#!.*python")) - mercurial/thirdparty/**'`