Re: BUG? git log --no-merges shows grafted merges in shallow clones

Matthieu Moy [off-list ref] writes:

Hi,

I don't think that's intended. When running "git log --no-merges" in a
shallow clone, and the last commit in the history is a merge commit,
"git log --no-merges" still shows it.

I've just hit this in a test running on a --depth=50 clone on Travis-CI
on git-multimail:

$ git cat-file -p c3c1cc25b27d448e9ef67b265a11be8735ff2df4
tree c341dd60c4b639eac1d6dcc3caffb5d7201c2245
parent b312e3f90dfef73ba0288999981694b09affdf6b
parent 842ac6e867885af041499723dc46f2197705204c
author Matthieu Moy [off-list ref] 1441031540 +0200
committer Matthieu Moy [off-list ref] 1441031540 +0200

Merge remote-tracking branch 'edward/utf-8-email-support4'

$ git log --no-merges c3c1cc25b27d448e9ef67b265a11be8735ff2df4
commit c3c1cc25b27d448e9ef67b265a11be8735ff2df4 (grafted)
Author: Matthieu Moy [off-list ref]
Date:   Mon Aug 31 16:32:20 2015 +0200

    Merge remote-tracking branch 'edward/utf-8-email-support4'

I guess Git counts the number of parents that are actually in the
repository, but it could check the number of "parents" field in the
object (cat-file -p was still able to show 2).

I do not think this is limited to shallow but for grafts in
general.  cat-file is low-level to show the bare metal, but by using
these facility you asked Git to give you an imaginary history where
that commit is the root commit--and that is why it is shown, I
think.

What does it do if you say "git -c log.showRoot=false log -p"?