Unexpected behavior of replacing chars by `R` command from normal mode

[jeffreytse]

Reproduce

• Open a new terminal.
• Input the content as below.

foo
bar
baz

• Put the cursor at the second "o".
• Enter normal mode and press R and ww.

Result

The second line was joined to above line as below.

fowwbar
baz

Expected behavior

The second line should not be joined to above line.

foww
bar
baz