Build error - Githubissues

Recently tried to install obus 1.1.6 on the 4.03.0+flambda opam switch, and got the following error:
#=== ERROR while installing obus.1.1.6 ========================================#
# opam-version 1.2.2
# os           linux
# command      ocaml setup.ml -build
# path         /home/guigui/.opam/4.03.0+flambda/build/obus.1.1.6
# compiler     4.03.0+flambda
# exit-code    1
# env-file     /home/guigui/.opam/4.03.0+flambda/build/obus.1.1.6/obus-21851-d2c37b.env
# stdout-file  /home/guigui/.opam/4.03.0+flambda/build/obus.1.1.6/obus-21851-d2c37b.out
# stderr-file  /home/guigui/.opam/4.03.0+flambda/build/obus.1.1.6/obus-21851-d2c37b.err
### stdout ###
# [...]
# Error: Multiple definition of the extension constructor name Service_unknown.
#        Names must be unique in a given structure or signature.
# Command exited with code 2.
# + /home/guigui/.opam/4.03.0+flambda/bin/ocamlopt.opt unix.cmxa -I /home/guigui/.opam/4.03.0+flambda/lib/ocamlbuild /home/guigui/.opam/4.03.0+flambda/lib/ocamlbuild/ocamlbuildlib.cmxa myocamlbuild.ml /home/guigui/.opam/4.03.0+flambda/lib/ocamlbuild/ocamlbuild.cmx -o myocamlbuild
# File "myocamlbuild.ml", line 492, characters 43-62:
# Warning 3: deprecated: Ocamlbuild_plugin.String.uncapitalize
# Use String.uncapitalize_ascii instead.
# File "myocamlbuild.ml", line 505, characters 51-70:
# Warning 3: deprecated: Ocamlbuild_plugin.String.uncapitalize
# Use String.uncapitalize_ascii instead.
### stderr ###
# [...]
# W: Cannot find source file matching module 'UPower_interfaces' in library obus-upower
# W: Cannot find source file matching module 'Nm_interfaces' in library obus-network-manager
# W: Cannot find source file matching module 'Nm_interfaces' in library obus-network-manager
# W: Cannot find source file matching module 'Notification_interfaces' in library obus-notification
# W: Cannot find source file matching module 'Notification_interfaces' in library obus-notification
# W: Cannot find source file matching module 'Hal_interfaces' in library obus-hal
# W: Cannot find source file matching module 'Hal_interfaces' in library obus-hal
# W: Cannot find source file matching module 'OBus_interfaces' in library obus
# W: Cannot find source file matching module 'OBus_interfaces' in library obus
# E: Failure("Command ''/home/guigui/.opam/4.03.0+flambda/bin/ocamlbuild' src/obus.cma src/obus.cmxa src/obus.a src/obus.cmxs src/obus-idl.cma src/obus-idl.cmxa src/obus-idl.a src/obus-idl.cmxs syntax/obus-syntax.cma bindings/hal/obus-hal.cma bindings/hal/obus-hal.cmxa bindings/hal/obus-hal.a bindings/hal/obus-hal.cmxs bindings/notification/obus-notification.cma bindings/notification/obus-notification.cmxa bindings/notification/obus-notification.a bindings/notification/obus-notification.cmxs bindings/network-manager/obus-network-manager.cma bindings/network-manager/obus-network-manager.cmxa bindings/network-manager/obus-network-manager.a bindings/network-manager/obus-network-manager.cmxs bindings/upower/obus-upower.cma bindings/upower/obus-upower.cmxa bindings/upower/obus-upower.a bindings/upower/obus-upower.cmxs bindings/udisks/obus-udisks.cma bindings/udisks/obus-udisks.cmxa bindings/udisks/obus-udisks.a bindings/udisks/obus-udisks.cmxs bindings/policykit/obus-policykit.cma bindings/policykit/obus-policykit.cmxa bindings/policykit/obus-policykit.a bindings/policykit/obus-policykit.cmxs tools/obus_gen_interface.native tools/obus_dump.native tools/obus_gen_client.native tools/obus_gen_server.native tools/obus_xml2idl.native tools/obus_idl2xml.native tools/obus_introspect.native examples/bus_functions.native examples/eject.native examples/hello.native examples/list_services.native examples/monitor.native examples/notify.native examples/ping.native examples/pong.native examples/signals.native examples/network_manager.native examples/battery_monitoring.native -tag debug' terminated with error code 10")
ocaml-community / obus

Build error #4
