x/build: git errors with gnutls_handshake() failed: Error in the pull function.

[bcmills]

            > go get -d insecure.go-get-issue-15410.appspot.com/pkg/p
            [stderr]
            # cd $WORK/gopath/src/insecure.go-get-issue-15410.appspot.com; git clone -- http://insecure.go-get-issue-15410.appspot.com/ $WORK/gopath/src/insecure.go-get-issue-15410.appspot.com/pkg
            Cloning into '$WORK/gopath/src/insecure.go-get-issue-15410.appspot.com/pkg'...
            fatal: unable to access 'http://insecure.go-get-issue-15410.appspot.com/': gnutls_handshake() failed: Error in the pull function.
            package insecure.go-get-issue-15410.appspot.com/pkg/p: exit status 128

greplogs -l -e 'gnutls_handshake() failed: Error in the pull function.'`
2022-05-09T20:57:58-3f43096/linux-386-longtest
2021-12-13T16:44:13-acc65b4/linux-amd64-longtest
2021-11-08T14:49:56-ab31dbc/linux-386-longtest
2021-10-26T15:20:53-1b2362b/linux-386-longtest
2021-10-23T16:18:15-12e4404/linux-386-longtest
2021-10-20T20:39:29-1dff8f0/linux-386-longtest
2021-10-20T05:28:45-b091189/linux-386-longtest
2021-10-20T05:28:45-b091189/linux-amd64-longtest
2021-10-19T18:56:08-07e5527/linux-386-longtest
2021-10-19T18:43:08-1d63052/linux-386-longtest
2021-10-19T18:18:37-9820602/linux-386-longtest
2021-10-11T22:34:49-d90f0b9/linux-386-longtest
2021-09-08T11:57:03-9295723/linux-386-longtest
2021-04-11T15:56:20-189c694/linux-amd64-longtest
2021-04-06T21:25:55-0bc4605/linux-386-longtest
2021-04-03T21:06:18-9e7bc80/linux-386-longtest
2020-10-29T16:26:43-25d28ec/linux-386-longtest

[bcmills]

I suspect that this indicates some kind of network error or internal server error, but it would be nice to get a better error message out of it.

Some cursory searching suggests:

• Upgrade git. (linux-386-longtest currently has git version 2.30.2, whereas the current release is 2.36.1)
• Upgrade libcurl3-gnutls (linux-386-longtest has 7.74.0, current is 7.83.0)
• Upgrade libgnutls30(linux-386-longtest has 3.7.1-5, current is 3.7.4-2)