net/http: don't reuse connections that are experiencing errors [1.20 backport]

[btasker]

Requesting that #59690 be considered for backport into the next 1.20 minor release

Relevant change in Gerrit is https://go-review.googlesource.com/c/net/+/486156

Rationale:

When encountered, this is a serious issue: requests are blocked until the kernel gives up on the socket (with default settings on a Linux host, that's around 17 minutes). If the operator restarts the application as a result, data loss may occur.

Although the fix is in x/net v0.10.0 it will not be available to most developers who likely import net/http (and so rely on the h2 bundle rolled into Go's releases)

The only viable workaround is to disable the H2 client entirely via environment variable.

[mdempsky]

@neild What do you think about this?

Also, is this applicable to 1.19?

[mknyszek]

Friendly ping @neild. :)

[ianlancetaylor]

Opened #60662 for a 1.19 backport.