"Detected x file renames" for copies

"Detected x file renames" for copies

[Michael J Gruber]

Hi there,

I noticed the following:
- have file f indexed by notmuch
- copy message file to a different folder using `notmuch insert --folder=Y < f`
- run notmuch new
This results in "Detected x file renames" if you do that for x files.

I have not checked whether this depends on folder names or on which
file copy notmuch considers as "the" message file. Probably this comes
from being able to find the message by filename or not in
notmuch.c:remove_filename().

I find "renames" confusing because it's the same message when you
actually move files, i.e. delete the original. But I"m wondering
whether it's worth investigating. I know not to be surprised now :)

Michael