the problem is not cmd/dist's. The builder will generate a VERSION file
containing only the sha1 commit hash.
That was necessary because hg clone is so slow on certain builders, and I
switched to hg export, which sped
up the process at least 10x on the slower builders, but without the .hg
directory, cmd/dist can't figure out the
version, so a hard-coded VERSION file was generated by the builder.

Now that we switched to git, we don't need that speed hack anymore.

Do we still need to support hg in tools/dashboard/builder? If not, we can
get rid of the VERSION file creation step entirely. (Or we can switch hg
to use clone instead of archive)

My last comment had a typo, it should be "hg archive" not "hg export".

We can drop hg support.

OK. I will do some test on the netbsd-386 builder.
And send a CL.

@bradfitz, could you clear the result for netbsd-386-minux builder
from the dashboard? To debug my changes, I need the dashboard
to give the builder some work to do. Thanks.

We don't have an easy+safe way to clear a result or row or column from the dashboard yet. We should have such a mechanism.

Before we have a tool, I'm reluctant to touch anything by hand.

My changes are working now. However it seems Gerrit has disabled upload from unregistered users.

Here is the patch: https://gist.github.com/minux/c2b1c270ac1c7ea1a0cc

However it seems Gerrit has disabled upload from unregistered users.

Gerrit has never allowed unauthenticated uploads. What do you mean?

But I don't think your patch is quite what we want. We still want to re-use the git repo $GOROOT we place at /goroot in the Linux docker images as a base, and only git pull up from that to our target build hash.

I fear that your patch will cause way too many git clone operations, which weigh in at 50+ MB each, and lots of disk I/O.

This is the error I was getting:
$ git push origin HEAD:refs/for/master
fatal: remote error: Upload denied for project 'tools'

I also tried to create a change on the web interface, but I got the same
error for both tools and go.

My patch doesn't change how the git repository is handled. The current
builder will always git clone
a new workspace, and git clone will use hard links for the .git directory
if possible. (git clone is
even faster than hg archive last time i benchmarked....)

Oh, I see we've disabled people without +2 from pushing changes, until we fix some Gerrit configuration things about the CLA checks.

@minux, you should be able to upload again.

Thanks very much, @bradfitz, I've mailed golang.org/cl/1510

I did intend for the cmd/dist/build.c change to yield "devel ", but @rsc was getting me to make a bunch of changes during its review and I think it slipped aside in the process. I can look into fixing that tomorrow if no-one has already started.

I went to start fixing cmd/dist, but couldn't see how the code could be omitting "devel". A quick experiment showed that it is working correctly at tip:

$ go version
go version devel +e5ee9a8 Sun Dec 14 23:54:15 2014 +0000 linux/amd64
$ cat > x.go
package main
import "runtime"
func main() { println(runtime.Version()) }
$ go run x.go
devel +e5ee9a8 Sun Dec 14 23:54:15 2014 +0000

So cmd/dist is working fine at tip.