util.copyfiles: don't try os_link() again if it failed before
If the os_link() call on the first file in the directory fails [1],
we switch mode to using shutil.copy() for all remaining files.
[1] happens for example on Windows for every file when cloning from a UNC
path without specifying --pull.
#!/bin/sh
"$TESTDIR/hghave" symlink || exit 80
hg init a
cd a
echo '% directory moved and symlinked'
mkdir foo
touch foo/a
hg ci -Ama
mv foo bar
ln -s bar foo
echo '% now addremove should remove old files'
hg addremove