lava · November 21, 2018 13:54 · Nov 21, 2018 · Nov 21, 2018 · Nov 21, 2018
diff --git a/git_merge.md b/git_merge.md
@@ -69,6 +69,39 @@ direction to get the PR number:
     8e5204a Add second.
 
 
+## Showing a history with only "correct" merges
+
+For this I tried adding new branch `fourth` (basing off master) and `initial2` (basing off the initial commit) where `initial2`
+is merged into `fourth` before `fourth` is merged into master using `--no-ff`.
+
+    bevers@poincare:~/code/git$ git log --graph --oneline
+    *   35fc573 (HEAD -> master) Merge branch 'fourth'
+    |\  
+    | *   195e250 (fourth) Merge branch 'initial2' into fourth
+    | |\  
+    | | * 509c299 (initial2) Add initial2.
+    | * | c133ca1 Add fourth.
+    |/ /  
+    * |   044c523 Merge branch 'third'
+    |\ \  
+    | * | 080a881 Third.
+    |/ /  
+    * |   ab286d7 Merge branch 'second'
+    |\ \  
+    | |/  
+    |/|   
+    | * 8e5204a Add second.
+    |/  
+    * 66ee9d4 Initial.
+
+It looks like this makes it very hard to view a history with only the merge commits where branches where merged into master:
+
+    35fc573 (HEAD -> master) Merge branch 'fourth'
+    195e250  Merge branch 'initial2' into fourth
+    044c523 Merge branch 'third'
+    ab286d7 Merge branch 'second'
+
+
 ## Bisecting on merge commits
 
 I wanted to try this as well since it came up in the comments, but

diff --git a/gistfile1.txt → git_merge.md b/gistfile1.txt → git_merge.md
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,75 @@
+# Testing the `--no-ff` merge strategy
+
+I created a sample git repository by creating branches
+`second` and `third` adding a file with the same name
+each, and then rebasing the branches and merging them
+using `git merge --no-ff`:
+
+    bevers@poincare:~/code/git$ ls
+    initial  second  third
+
+    bevers@poincare:~/code/git$ git log --graph --oneline
+    *   044c523 (HEAD -> master) Merge branch 'third'
+    |\  
+    | * 080a881 Third.
+    |/  
+    *   ab286d7 Merge branch 'second'
+    |\  
+    | * 8e5204a Add second.
+    |/  
+    * 66ee9d4 (first2) Initial.
+
+Below I list several observations.
+
+## Behaviour of `HEAD`
+
+    bevers@poincare:~/code/git$ git log --oneline
+    044c523 (HEAD -> master) Merge branch 'third'
+    080a881 Third.
+    ab286d7 Merge branch 'second'
+    8e5204a Add second.
+    66ee9d4 Initial.
+
+    bevers@poincare:~/code/git$ git show --oneline HEAD~1
+    ab286d7 Merge branch 'second'
+
+I would have expected `HEAD~1` to point at `080a881`.
+
+
+## Viewing the contents of commits
+
+    bevers@poincare:~/code/git$ git log --stat --oneline
+    044c523 (HEAD -> master) Merge branch 'third'
+    080a881 Third.
+     third | 0
+     1 file changed, 0 insertions(+), 0 deletions(-)
+    ab286d7 Merge branch 'second'
+    8e5204a Add second.
+     second | 0
+     1 file changed, 0 insertions(+), 0 deletions(-)
+    66ee9d4 (first2) Initial.
+     initial | 0
+     1 file changed, 0 insertions(+), 0 deletions(-)
+
+    bevers@poincare:~/code/git$ git log --stat --oneline --merges
+    044c523 (HEAD -> master) Merge branch 'third'
+    ab286d7 Merge branch 'second'
+
+    bevers@poincare:~/code/git$ git log -p --oneline --merges
+    044c523 (HEAD -> master) Merge branch 'third'
+    ab286d7 Merge branch 'second'
+
+This also has implications for tasks like finding out the PR in
+which a particular file was last touched: Because the merge
+commit itself does not change the file, it does not show up in
+`git blame` etc. and we would have to walk the log in reverse
+direction to get the PR number:
+
+    bevers@poincare:~/code/git$ git log --oneline -- second
+    8e5204a Add second.
+
+
+## Bisecting on merge commits
+
+I wanted to try this as well since it came up in the comments, but
+I don't know how to do it. Suggestions?