git show -- output only displays summary

Question

I'm having trouble with all git commands that display the log/history of a repository. This issue is ONLY limitied to one of my repositories. I have several others that work just fine.

For the repo with issues, I only see the summary of the commit, where as the default behavior is to display the diff as well.

$ git show
  commit bc8865f8b16ccf9eerrt678df99a4b89e73c0545
  Merge: 677f483 3e8617d
  Author: Some Author
  Date:   Thu Jul 23 07:56:28 2015 -0400

  Merge branch 'Some_branch' ....

Similarly, the git diff-tree command works fine with all repos except for this one.

Normal Repo:

git diff-tree --pretty=format:%an %cn 5cff917e
Joe Black Joe Black
:040000 040000 98c97ee8929b487ae14ada67c1932205a80cfc3f 719f1764f123d462b20707f5f7740e4f473b2b47 M  oracle

Repo with issues:

$ git diff-tree --pretty=format:%an 39ebdeb8f29

jblack@DFX1 ~/repositories/RepoName(master)

Answer 1

You are running git show on a merge commit:

Merge: 677f483 3e8617d

There is no unique way to show the diff for a merge commit: this commit has two parents, you can diff with either of them. To show the diff with each parent, use

git show -m <commit>

Answer 2

From the git show docs:

For commits it shows the log message and textual diff. It also presents the merge commit in a special format as produced by git diff-tree --cc.

and from the git diff-tree docs:

--cc
This flag changes the way a merge commit patch is displayed, in a similar way to the -c option. It implies the -c and -p options and further compresses the patch output by omitting uninteresting hunks whose the contents in the parents have only two variants and the merge result picks one of them without modification. When all hunks are uninteresting, the commit itself and the commit log message is not shown, just like in any other "empty diff" case.

So for merges, show by default won't bother you with changes that automerge handled silently for you. As Matthieu Moy points out, to see all the changes regardless, feed it -m.