rebase - How to linearize "splintered" merging history in Git? -

it must obvious, found no way it. every manual describes rebasing onto top of existing branch or simple interactive rebase , that's all. suppose, have diamond-shaped git history that:

*   949430f merge commit (d) (head, mybranch) |\   | * e6a2e8b (c) * | 3e653ff (b) |/   *   9c3641f base commit (a) 

and want archieve history like:

*   949430f combined commit (bcd) |   *   9c3641f base commit (a) 

commits b , c may melted or discarded @ all, doesn't matter, want preserve result. not want revert commits because of nasty conficts resolving.

here things i've tried:

1) can't archeve simple squashing b , c

git rebase -i head~2 ... p 3e653ff (b) f e6a2e8b (c) ... not apply a91f3a4 

well, that's understandable, there're conflicts.

2) can't archeve squashing.

git rebase -i -p head~3 ... pick 9c3641f base commit (a) f 3e653ff (b) f e6a2e8b (c) pick 949430f merge commit (d) ... error: unable match a91f3a4... 

3) can't discard b , c

git rebase -i -p -m head~3 ... pick 9c3641f base commit (a) #pick 3e653ff (b) #pick e6a2e8b (c) pick 949430f merge commit (d) ... error: commit 949430f merged option -m not set. fatal: cherry-pick failed not pick 4f3e6231b5cecf57434613ca3afd2a21ba375eb9 

why? here option "-m"...

does know how solve problem?

what want git reset --soft (plus a commit noted aragaer). despite different circumstances in question, see this answer vonc.