Test ubuntu-20.04-64:tests/main/uc20-create-partitions flaky

[Ian Johnson]

The test sometimes fails with

Error: 2021-11-02 22:41:48 Error executing google:ubuntu-20.04-64:tests/main/uc20-create-partitions (nov022215-402180) :
-----
++ cat loop.txt
+ LOOP=/dev/loop3
+ echo 'Run the snap-bootstrap tool'
Run the snap-bootstrap tool
+ go get ../../lib/uc20-create-partitions
go: finding github.com/canonical/go-tpm2 v0.0.0-20210827151749-f80ff5afff61
go: finding github.com/mvo5/goconfigparser v0.0.0-20200803085309-72e476556adb
go: finding github.com/snapcore/secboot v0.0.0-20211018143212-802bb19ca263
go: finding github.com/canonical/go-sp800.108-kdf v0.0.0-20210314145419-a3359f2d21b9
go: finding github.com/canonical/go-efilib v0.0.0-20210909101908-41435fa545d4
go: finding github.com/canonical/tcglog-parser v0.0.0-20210824131805-69fa1e9f0ad2
go: finding github.com/canonical/go-sp800.90a-drbg v0.0.0-20210314144037-6eeb1040d6c3
go: finding go.mozilla.org/pkcs7 v0.0.0-20200128120323-432b2356ecb1
go: finding maze.io/x/crypto v0.0.0-20190131090603-9b94c9afe066
+ kerneldir=
+ uc20-create-partitions ./gadget-dir '' /dev/loop3
+ echo 'And check that the partitions are created'
And check that the partitions are created
+ MATCH '750M Linux filesystem'
+ sfdisk -l /dev/loop3
+ MATCH '16.7G Linux filesystem'
+ sfdisk -l /dev/loop3
+ MATCH 'ext4 filesystem data,.* volume name "ubuntu-boot"'
+ file -s /dev/loop3p3
+ MATCH 'ext4 filesystem data,.* volume name "ubuntu-save"'
+ file -s /dev/loop3p4
+ MATCH 'ext4 filesystem data,.* volume name "ubuntu-data"'
+ file -s /dev/loop3p5
+ echo 'Check that the filesystems were not auto-mounted'
Check that the filesystems were not auto-mounted
+ NOMATCH /run/mnt/ubuntu-seed
+ mount
+ NOMATCH /run/mnt/ubuntu-boot
+ mount
+ NOMATCH /run/mnt/ubuntu-save
+ mount
+ NOMATCH /run/mnt/ubuntu-data
+ mount
+ mkdir -p ./mnt
+ mount /dev/loop3p2 ./mnt
+ MATCH vfat
+ df -T /dev/loop3p2
+ umount ./mnt
+ mkdir -p ./mnt
+ mount /dev/loop3p3 ./mnt
+ df -T /dev/loop3p3
+ MATCH ext4
+ umount ./mnt
+ MATCH 'ext4 filesystem data,.* volume name "ubuntu-boot"'
+ file -s /dev/loop3p3
+ MATCH '^Filesystem features:.*metadata_csum'
+ tune2fs -l /dev/loop3p3
+ mkdir -p ./mnt
+ mount /dev/loop3p4 ./mnt
+ df -T /dev/loop3p4
+ MATCH ext4
+ umount ./mnt
+ MATCH 'ext4 filesystem data,.* volume name "ubuntu-save"'
+ file -s /dev/loop3p4
+ MATCH '^Filesystem features:.*metadata_csum'
+ tune2fs -l /dev/loop3p4
+ mkdir -p ./mnt
+ mount /dev/loop3p5 ./mnt
+ MATCH ext4
+ df -T /dev/loop3p5
+ umount ./mnt
+ MATCH 'ext4 filesystem data,.* volume name "ubuntu-data"'
+ file -s /dev/loop3p5
+ MATCH '^Filesystem features:.*metadata_csum'
+ tune2fs -l /dev/loop3p5
++ cut -f2 -d=
++ grep '^ID_PART_ENTRY_SIZE='
++ udevadm info -q property /dev/loop3p5
+ sz=35032003
+ '[' 35032003 -lt 20971520 ']'
+ echo 'Check that the filesystem content was deployed'
Check that the filesystem content was deployed
+ mkdir -p ./mnt
+ mount /dev/loop3p3 ./mnt
+ ls ./mnt/EFI/boot/grubx64.efi
./mnt/EFI/boot/grubx64.efi
+ ls ./mnt/EFI/boot/bootx64.efi
./mnt/EFI/boot/bootx64.efi
+ rm ./mnt/EFI/boot/grubx64.efi
+ umount ./mnt
+ echo 'now add a partition'
now add a partition
+ cat
+ uc20-create-partitions --mount ./gadget-dir '' /dev/loop3
panic: cannot mount filesystem "/dev/loop3p4" at "/run/mnt/ubuntu-save": bad message

goroutine 1 [running]:
main.main()
 /home/gopath/src/github.com/snapcore/snapd/tests/lib/uc20-create-partitions/main.go:81 +0x665

Debug output available at https://pastebin.ubuntu.com/p/Rmd7Jvbzpn/