So I applied Victor's `route[TEST]` at the beginning of my config and added the usrloc entries. The problem with branches could not be reproduced. Instead of `drop` at the end of `route[TEST]`, I `revert_uri()` so I could continue with my `append_branch` portion. Same result. Here's the log (DEBUG=2).
``` ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: Entering test route ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== $ru:sip:alice5@127.0.0.5:5085 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === $branch 0: uri:sip:alice4@127.0.0.4:5084, q:400 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === $branch 1: uri:sip:alice3@127.0.0.3:5083, q:300 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === $branch 2: uri:sip:alice2@127.0.0.2:5082, q:200 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === $branch 3: uri:sip:alice1@127.0.0.1:5081, q:100 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === $branch 4: uri:<null>, q:<null> ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== $ru:sip:alice5@127.0.0.5:5085 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== $ru:sip:alice4@127.0.0.4:5084 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== $ru:sip:alice3@127.0.0.3:5083 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== $ru:sip:alice2@127.0.0.2:5082 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== $ru:sip:alice1@127.0.0.1:5081 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: Starting append_branch() sequence ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === sip:1001@gateway1.carrierB.com;transport=tcp, 300 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === sip:1001@gateway2.carrierB.com;transport=tcp, 200 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === sip:1001@gateway3.carrierB.com;transport=tcp, 700 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === sip:1001@gateway4.carrierB.com;transport=tcp, 500 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: === sip:1001@gateway5.carrierB.com;transport=tcp, 600 ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: Starting t_next_contacts ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== sip:alice@carrierB ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== sip:1001@gateway5.carrierB.com;transport=tcp ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== sip:1001@gateway4.carrierB.com;transport=tcp ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== sip:1001@gateway1.carrierB.com;transport=tcp ERROR: sipp-ci1-20200827020223-1-21@172.19.1.21: ==== sip:1001@gateway2.carrierB.com;transport=tcp ```