Avoid erroring when processing emails again

These changes allow processing emails again, and just creating job and branch
entries where data is missing.

sqitch/deploy/remove_duplicate_load_new_guix_revision_jobs.sql

@@ -0,0 +1,25 @@
+-- Deploy guix-data-service:remove_duplicate_load_new_guix_revision_jobs to pg
+
+BEGIN;
+
+DELETE FROM load_new_guix_revision_job_events WHERE job_id NOT IN (
+  SELECT MIN(id) FROM load_new_guix_revision_jobs
+  GROUP BY commit, git_repository_id
+);
+
+DELETE FROM load_new_guix_revision_job_logs WHERE job_id NOT IN (
+  SELECT MIN(id) FROM load_new_guix_revision_jobs
+  GROUP BY commit, git_repository_id
+);
+
+DELETE FROM load_new_guix_revision_jobs WHERE id NOT IN (
+  SELECT MIN(id) FROM load_new_guix_revision_jobs
+  GROUP BY commit, git_repository_id
+);
+
+CREATE UNIQUE INDEX ON load_new_guix_revision_jobs (
+  commit,
+  git_repository_id
+);
+
+COMMIT;

sqitch/revert/remove_duplicate_load_new_guix_revision_jobs.sql

@@ -0,0 +1,7 @@
+-- Revert guix-data-service:remove_duplicate_load_new_guix_revision_jobs from pg
+
+BEGIN;
+
+-- XXX Add DDLs here.
+
+COMMIT;

sqitch/sqitch.plan

@@ -17,3 +17,4 @@ load_new_guix_revision_job_logs 2019-06-21T14:33:09Z chris <chris@phact> # Add l
 change_load_new_guix_revision_job_logs_contents_to_be_nullable 2019-07-07T20:10:54Z Christopher Baines <mail@cbaines.net> # Change the contents field in the load_new_guix_revision_job_logs table\nto be nullable.\n\nwith '#' will # be ignored, and an empty message aborts the add.  #\nChange to add: # #\nchange_load_new_guix_revision_job_logs_contents_to_be_nullable #\nsqitch/deploy/change_load_new_guix_revision_job_logs_contents_to_be_nullable.sql\nsqitch/revert/change_load_new_guix_revision_job_logs_contents_to_be_nullable.sql\nsqitch/verify/change_load_new_guix_revision_job_logs_contents_to_be_nullable.sql
 fix_duplicated_licenses 2019-07-30T05:48:17Z Christopher Baines <mail@cbaines.net> # Fix duplicated licenses, and add constraints
 change_git_branches_primary_key 2019-08-05T18:57:41Z Christopher Baines <mail@cbaines.net> # Change the git_branches primary key to include the git_repository_id,\nas this will allow having the same branch in different repositories.
+remove_duplicate_load_new_guix_revision_jobs 2019-08-05T19:06:36Z Christopher Baines <mail@cbaines.net> # Remove duplicate load_new_guix_revision_jobs

sqitch/verify/remove_duplicate_load_new_guix_revision_jobs.sql

@@ -0,0 +1,7 @@
+-- Verify guix-data-service:remove_duplicate_load_new_guix_revision_jobs on pg
+
+BEGIN;
+
+-- XXX Add verifications here.
+
+ROLLBACK;