tail -F (and -f) does not detect appends to a regular file on Linux

Version: uutils tail 0.2.2 (Ubuntu 25.10 / questing)
Platform: Linux x86_64

Minimal repro:

tmp=$(mktemp -d)
echo "fileA-line1" > $tmp/A
ln $tmp/A $tmp/now
script -qc "tail -F $tmp/now & sleep 6; kill %1" $tmp/out < /dev/null > /dev/null 2>&1 &
sleep 1
echo "fileB-line1" > $tmp/B
ln $tmp/B $tmp/now.tmp
mv -f $tmp/now.tmp $tmp/now    # atomic hard-link replacement
sleep 1
echo "fileB-line2" >> $tmp/B   # NOT shown — bug
sleep 3
wait
cat $tmp/out

Actual output:

fileA-line1
tail: '<tmpdir>/now' has been replaced;  following new file
fileB-line1

Expected (matches GNU tail 9.5):

fileA-line1
tail: '<tmpdir>/now' has been replaced;  following new file
fileB-line1
fileB-line2

So replacement is correctly detected and the new file's initial content is read once, but IN_MODIFY events on the new inode are not handled — appends to the new file after the swap are silently missed.

Same behavior with tail -f (lowercase).

script is just to give tail a PTY so output isn't block-buffered; reproduces identically with a real interactive shell.

Start by running the provided Linux reproduction for tail -F and tail -f, then trace the file-replacement and event-handling paths in the tail implementation. Confirm that IN_MODIFY events for the replacement inode are handled after the initial content is read, and verify that fileB-line2 appears in both modes.