Merge ~mwhudson/curtin:lp-1876626 into curtin:master

[Michael Hudson-Doyle]

block.detect_multipath: ignore fake "devices" from /proc/mounts

A tmpfs can be mounted with any old junk in the "device" field and
unfortunately casper sometimes puts "/dev/shm" there, which is usually a
directory. Ignore such cases.

LP: #1876626

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:61a11664e749d216555e0241335717f538cca22c
https://jenkins.ubuntu.com/server/job/curtin-ci/73/
Executed test runs:
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-amd64/73/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-arm64/73/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-ppc64el/73/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-s390x/73/

Click here to trigger a rebuild:
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review: Approve (continuous-integration)

[Ryan Harper (raharper)]

Thanks!

review: Approve

[Server Team CI bot (server-team-bot)]

Commit message lints:
- Line #4 has 2 too many characters. Line starts with: "directory. Ignore such"...

review: Needs Fixing

[Server Team CI bot (server-team-bot)]

Autolanding: FAILED
More details in the following jenkins job:
https://jenkins.ubuntu.com/server/job/curtin-autoland-test/166/
Executed test runs:
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-autoland-test/nodes=metal-amd64/166/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-autoland-test/nodes=metal-arm64/166/
    FAILURE: https://jenkins.ubuntu.com/server/job/curtin-autoland-test/nodes=metal-ppc64el/166/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-autoland-test/nodes=metal-s390x/166/

review: Needs Fixing (continuous-integration)

[Ryan Harper (raharper)]

Spurious failure on ppc64 node; could be lab vpn related; I was having some trouble as well. I think autolander will retry.

[Server Team CI bot (server-team-bot)]

review: Approve (continuous-integration)

diff --git a/curtin/block/__init__.py b/curtin/block/__init__.py
index a7fe22f..c006aa4 100644
--- a/curtin/block/__init__.py
+++ b/curtin/block/__init__.py
@@ -637,6 +637,12 @@ def detect_multipath(target_mountpoint=None):
         for device in (os.path.realpath(dev)
                        for (dev, _mp, _vfs, _opts, _freq, _passno)
                        in get_proc_mounts() if dev.startswith('/dev/')):
+            if not is_block_device(device):
+                # A tmpfs can be mounted with any old junk in the "device"
+                # field and unfortunately casper sometimes puts "/dev/shm"
+                # there, which is usually a directory. Ignore such cases.
+                # (See https://bugs.launchpad.net/bugs/1876626)
+                continue
             if _device_is_multipathed(device):
                 return device