Here is a concrete example:
lt-nkiesel:~Platform(nextrelease)% git -c rebase.backend=merge -c
pull.rebase=false -c branch.nextrelease.rebase=true pull
remote: Enumerating objects: 1, done.
remote: Counting objects: 100% (1/1), done.
remote: Total 1 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (1/1), 279 bytes | 279.00 KiB/s, done.
>From msgit.rnd.metricstream.com:platform/Platform7
d008080d3f2..db4042856da nextrelease -> origin/nextrelease
Updating d008080d3f2..db4042856da
Fast-forward
modules/bpcsfw/src/main/java/com/metricstream/systemi/client/servlet/servant/BaseViewController.java
| 54 +++++++++++++++++++++++++-----------------------------
modules/bpcsfw/src/main/java/com/metricstream/util/HttpUtils.java
| 5 +++++
2 files changed, 30 insertions(+), 29 deletions(-)
Successfully rebased and updated refs/heads/nextrelease.
lt-nkiesel:~Platform(nextrelease)% git rev-parse ORIG_HEAD
db4042856da8338f183c831fca92cf63da7988bd
lt-nkiesel:~Platform(nextrelease)% git rev-parse HEAD
db4042856da8338f183c831fca92cf63da7988bd
lt-nkiesel:~Platform(nextrelease)%
As you can see, git said "Fast-forward" (i.e. no need to rebase) but
nevertheless after that pull ORIG_HEAD is identical to HEAD
