gistfile1.txt

State A (current):

branch foo: A -- B -- C -- D
                           \
branch bar:                 -- E -- F -- G --H

I want commit E from bar brought back into foo, without cherry-picking and creating a new commit. Essentially I want to go to this:

State B:

branch foo: A -- B -- C -- D -- E
                                  \
branch bar:                        F -- G --H

$ git checkout foo
$ git merge <sha of commit E>

Seems to do what you want from what I just did locally.

mkdir -p ~/tmp/lukeredpath
cd !$

git init
# Rename master to foo
git branch -M foo

# Add commits A-D on `foo`
git commit --allow-empty -m "A"
git commit --allow-empty -m "B"
git commit --allow-empty -m "C"
git commit --allow-empty -m "D"

# Branch `bar` from `foo`
git checkout -b bar

# Add E-H on `bar`
git commit --allow-empty -m "E"
git commit --allow-empty -m "F"
git commit --allow-empty -m "G"
git commit --allow-empty -m "H"

# Go back to `foo`
git checkout foo

# Merge in commit "E" (SHA is the SHA of commit "E")
git merge 0b1ba4357d706cab759077b29c57570c9a6b2237

# Check log of `foo` contains E
git log

I think you could just do (from branch foo):

git reset --hard E

(where E is the sha reference to E)

This would point that branch at commit E. The history stays intact. This only won't work if you have further commits (not shown) on branch foo.