tests: extract wire protocol shell helpers to standalone file
This will make it easier for other tests to get up and running without
the boilerplate.
Differential Revision: https://phab.mercurial-scm.org/D3176
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
new changesets d326ae2d01ee
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
new changesets d326ae2d01ee
4 files updated, 0 files merged, 0 files removed, 0 files unresolved