Immediately after "git commit --amend" of a single commit,
this fails:
$ git format-patch --range-diff=@{1} -v2 HEAD^ HEAD
fatal: --range-diff requires --cover-letter or single patch
The intent is very clear. I know it is a single-patch topic, and I
want to show what I changed with "commit --amend" as a reference to
the previous version. These, on the other hand, that specify the
range of commits to be emitted correctly recognises that we are
talking about a single patch and does not fail.
$ git format-patch --range-diff=@{1} -v2 HEAD^
$ git format-patch --range-diff=@{1} -v2 -1
It seems to me that the traditional "format-patch <since> <until>"
notation, which is understood by everywhere else in format-patch, is
not correctly understood by the code for "--range-diff" to make this
complaint, to recognise that the given range has only a single commit.
