postgres-init-dev-db: Catch exception when recreating extant users.
postgres-init-dev-db: Catch exception when recreating extant users.

Signed-off-by: Anders Kaseorg <dfdb7392591db597bc41cf266a9c3bc12a2706e5@zulipchat.com>

synicalsyntax/zulip,eeshangarg/zulip,rht/zulip,showell/zulip,eeshangarg/zulip,synicalsyntax/zulip,rht/zulip,punchagan/zulip,timabbott/zulip,brainwane/zulip,punchagan/zulip,eeshangarg/zulip,showell/zulip,synicalsyntax/zulip,brainwane/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,zulip/zulip,brainwane/zulip,kou/zulip,zulip/zulip,rishig/zulip,rishig/zulip,eeshangarg/zulip,zulip/zulip,punchagan/zulip,shubhamdhama/zulip,brainwane/zulip,rht/zulip,rht/zulip,rishig/zulip,eeshangarg/zulip,rishig/zulip,timabbott/zulip,kou/zulip,showell/zulip,tommyip/zulip,tommyip/zulip,rht/zulip,punchagan/zulip,shubhamdhama/zulip,rishig/zulip,shubhamdhama/zulip,kou/zulip,andersk/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,rht/zulip,shubhamdhama/zulip,showell/zulip,kou/zulip,punchagan/zulip,tommyip/zulip,rishig/zulip,brainwane/zulip,eeshangarg/zulip,timabbott/zulip,synicalsyntax/zulip,tommyip/zulip,showell/zulip,kou/zulip,timabbott/zulip,showell/zulip,andersk/zulip,andersk/zulip,timabbott/zulip,showell/zulip,tommyip/zulip,rishig/zulip,timabbott/zulip,zulip/zulip,andersk/zulip,tommyip/zulip,brainwane/zulip,hackerkid/zulip,timabbott/zulip,punchagan/zulip,synicalsyntax/zulip,shubhamdhama/zulip,hackerkid/zulip,zulip/zulip,brainwane/zulip,shubhamdhama/zulip,andersk/zulip,rht/zulip,punchagan/zulip,andersk/zulip,hackerkid/zulip,tommyip/zulip,hackerkid/zulip,synicalsyntax/zulip,hackerkid/zulip,zulip/zulip,shubhamdhama/zulip,synicalsyntax/zulip,eeshangarg/zulip