Mercurial : Combine Revisions 1 and 4 only

Question

say i have a local clone called test that i am working on. test has 5 changesets as follows (4 being the latest changeset):

Test:
0 -- 1 -- 2 -- 3 -- 4

Q1. How can i merge / collapse / combine changeset 4 with changeset 1 (I do not want the diff of 2 and 3 included) so it looks like this (3 being the merged 1 and 4)

Test:
0 -- 1 -- 2 -- 3

Answer 1

1. Without MQ: Histedit extension
2. Using MQ extension: Editing History

Additional reading: Concatenating Changesets, Collapse Extension

PS: I'll prefer to use pure MQ-way