Fail when an unpickle succeeds but has extra junk data at the end.

Also adds tests to ensure this is working.
10 jobs for dkasak/fix-unpickling-error-handling in 7 minutes and 36 seconds (queued for 32 seconds)
Child pipeline (parent)
Status Job ID Name Coverage
  Build
passed build:python #24159

00:03:07

 
  Test
passed test:python: [3.6] #24162

00:01:32

passed test:python: [3.7] #24164

00:01:28

passed test:python: [3.8] #24165

00:02:58

passed test:python: [3.9] #24166

00:02:42

 
  Dist
passed dist:python:sdist #24167

00:00:54

passed dist:python:wheel: [3.6] #24168

00:01:10

passed dist:python:wheel: [3.7] #24169

00:00:58

passed dist:python:wheel: [3.8] #24170

00:01:07

passed dist:python:wheel: [3.9] #24171

00:01:29