snapd 2.28.5 ADT test failure with linux 4.4.0.101.106

There's an expect timeout while running the bash_completion ADT test.

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test-snapd-upower-observe-consumer
bash-4.3# snap install test
expect: does "\r\ntestflinger-cli\r\ntest-hello\r\ntest-snapd-auto-aliases\r\ntest-snapd-base-bare\r\ntest-snapd-busybox-static\r\ntest-snapd-classic-confinement\r\ntest-snapd-content-plug\r\ntest-snapd-content-slot\r\ntest-snapd-content-slot-no-content-attr\r\ntest-snapd-control-consumer\r\ntest-snapd-cups-control-consumer\r\ntest-snapd-dbus-service\r\ntest-snapd-delta-refresh\r\ntest-snapd-fuse-consumer\r\ntest-snapd-go-webserver\r\ntest-snapd-gsettings\r\ntest-snapd-network-status-consumer\r\ntest-snapd-python-webserver\r\ntest-snapd-thumbnailer-consumer\r\ntest-snapd-tools\r\ntest-snapd-uhid\r\n--More--\u0007\u0007\r\rtest-snapd-upower-observe-consumer\r\nbash-4.3# snap install test" (spawn_id exp3) match glob pattern "bash-*[$#] $"? no
expect: timed out
timeout
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Failing for linux-meta/4.4.0.101.106 on amd64:
https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-xenial/xenial/amd64/s/snapd/20171115_171404_017c3@/log.gz
and its derivatives.

Also failing on Xenial with HWE kernel (4.13):
https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-xenial/xenial/amd64/s/snapd/20171115_183735_00c29@/log.gz