[Bug go/64573] New: Cmd.Start swallows error from fork()/clone()

[eswierk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64573

            Bug ID: 64573
           Summary: Cmd.Start swallows error from fork()/clone()
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: go
          Assignee: ian at airs dot com
          Reporter: eswierk at gmail dot com
                CC: cmang at google dot com

Created attachment 34428
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34428&action=edit
Proposed fix

Cmd.Start ignores the error code from the underlying fork() or clone() syscall,
instead returning a nil error while setting Process.Pid to 0.  If the caller
then tries to Wait on the command, it can end up reaping some other child
process (since waitpid(0) means wait for any child in the process group).

The attached patch should make the behavior identical to that of golang.