Re: [PATCH OSSTEST v1] ap-fetch-version: Arrange for osstest merges from upstream to be stable

[Ian Campbell <ian.campbell@citrix.com>]

On Wed, 2015-07-08 at 16:26 +0100, Ian Campbell wrote:
> On Wed, 2015-07-08 at 16:23 +0100, Ian Jackson wrote:
> > Ian Campbell writes ("[PATCH OSSTEST v1] ap-fetch-version: Arrange for osstest merges from upstream to be stable"):
> > > If a downstream osstest instance has nothing to test it its local
> > > pretest then it will attempt to merge from the upstream instance. If
> > > this fails then it will try again and again generating a new merge
> > > commit each time, even if upstream has not moved.
> > > 
> > > It is desirable that these merges instead be stable i.e. the same if
> > > the inputs have not changed. This is good for potential bisection
> > > attempts, history reporting/mining as well as just being sensible.
> > > 
> > > Here we arrange for this by recording the last merge "epoch" (being
> > > the first merge of the current input branches) in a new branch
> > > "merge-epoch" in the local testing.git and comparing our fresh merge
> > > against it.
> > > 
> > > If the tree and parents are the same then the merge is effectively
> > > identical (it may/will differ in the date) and we reuse the epoch
> > > merge.
> > > 
> > > If they new merge does not match then something has changed (i.e.
> > > upstream has moved on) and so we take the new merge and establish a
> > > new epoch.
> > > 
> > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> > 
> > Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
> 
> Thanks. I've put this into the Cambridge instance's pretest, and will
> send a pull request to merge back the result when it has baked there.

This passed the Cambridge push gate but then turned out to be missing at
least one ">&2" on the git reset, which resulted in things leaking onto
stdout which should have been there and:

OSSTEST_REVISION='HEAD is now at 8f88bfa ap-fetch-version: Arrange for osstest merges from upstream to be stable
8f88bfa7ac682d4d0df7da206b239a062870c84c'

Needless to say things did not improve from there...

I've placed a stop file and am about to unwind the various things which
need unwinding and push a new version with >&2 added in the appropriate
places, including a couple of "git fetch" which seem to not need them in
practice (at least while things are operating normally), but for
robustness I added them.

Ian.