When rolling back include the git commits from the previous update

When referring to a serial in a previous update we need to refer to the commits from that update.

Updating the serial is not sufficient.

library/ubuntu

@@ -46,7 +46,20 @@ Directory: focal
 # 20190515 (trusty)
 Tags: 14.04, trusty-20190515, trusty
 Architectures: amd64, arm32v7, arm64v8, i386, ppc64le
+GitCommit: 7a1a4f883de2d81351a82c86c24a0033dcae03db
 Directory: trusty
+amd64-GitCommit: 010bf9649b1d10e2c34b159a9a9b338d0fdd4939
+amd64-GitFetch: refs/heads/dist-amd64
+arm32v7-GitCommit: b9a951ace1f2e2e418828a197f62678c337f903e
+arm32v7-GitFetch: refs/heads/dist-arm32v7
+arm64v8-GitCommit: dffe0ea71413c9ca297a0935bade25c3ad3348a3
+arm64v8-GitFetch: refs/heads/dist-arm64v8
+i386-GitCommit: 2f8e166f4a725c5bcf3e96e2986d312f39a14098
+i386-GitFetch: refs/heads/dist-i386
+ppc64le-GitCommit: bbbf38c2900bd6aea408e3690be45e74bf2de1a5
+ppc64le-GitFetch: refs/heads/dist-ppc64le
+s390x-GitCommit: 4f55bf693232c85b18f9e6084c8f6780a24c3ba4
+s390x-GitFetch: refs/heads/dist-s390x
 
 # 20191108 (xenial)
 Tags: 16.04, xenial-20191108, xenial