how about something like this (preserving the empty commit). The reason is that we need to tell that the empty commit is preserved more than the fact the commit is empty.
note the (, it makes it look like a help text.
I added a note: in front instead. I think we usually use parentheses for hints.
I also changed s/preserving/keeping/ to match the term we use in the --keep flag (and the upcoming config option).
I kind of like the all files uncommitted part since it explains what empty commit we're talking about. Should I add it back?
And I just realized that we do use parentheses quite frequently for non-hint notes too, such as for "(leaving bookmark test)" and "(no more unresolved files)". Examples of "note: " include "note: commit message saved in .hg/last-message.txt" and "note: graft of 27:17d42b8f5d50 created no changes to commit". It seems there are quite many of each, so it's not clear that one or the other is preferred. I like "note: " better, so I'll leave it as is unless someone else feels strongly.