One not-so-well-known feature of gerrit is that, you can set a
%base for the RevWalk in ReceiveCommits when pushing changes to
Gerrit. This makes it possible to push a commit for review and
override Gerrits default algorithm for creating new changes on
push to refs/for/*. For instance, one could submit a commit in
a private branch and, afterward, push the same commit to a
release branch.
Specifying the tip of the destination branch as the %base would
have an effect of creating a new change for every commit reachable
from the pushed commit and not reachable from the target branch.
This behavior seems to be wanted by some Gerrit users and is
implemented as a project config option by this change (although
it contradicts the Gerrit's philosophy of reviewing one commit once).
If a %base is explicitly set on during uploading changes,
new-change-for-all-not-in-target is ignored.
To avoid incidental pushes with merges,
new-change-for-all-not-in-target rejects uploads if changes
contain merge commits. In such cases to push a merge commit, you
need to explicitly set the %base parameter as described in
Uploading Changes / Selecting Merge Base documentation.
Bug: issue 1195
Change-Id: Ifa90184352c912885e52d2060356fcc039d0ef03
52777270d9