Merge ~smoser/cloud-init:bug/ds-identify-none-twice into cloud-init:master

[Scott Moser]

ds-identify: do not write None twice to datasource_list.

If the only the None datasource was listed in datasource_list, then
ds-identify would write a cloud.cfg witih:
 datasource_list: [None, None]

The fix is to just append None if the list only has None.

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

PASSED: Continuous integration, rev:841f1fc340f3827b74a3348c5e3531c0e7504949
https://jenkins.ubuntu.com/server/job/cloud-init-ci/171/
Executed test runs:
    SUCCESS: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-amd64/171
    SUCCESS: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-arm64/171
    SUCCESS: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-ppc64el/171
    SUCCESS: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-s390x/171
    SUCCESS: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=vm-i386/171

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/171/rebuild

review: Approve (continuous-integration)

[Dan Watkins (oddbloke)]

review: Approve

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

FAILED: Continuous integration, rev:0
https://jenkins.ubuntu.com/server/job/cloud-init-ci/183/
Executed test runs:
    FAILURE: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-amd64/183/console
    FAILURE: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-arm64/183/console
    FAILURE: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-ppc64el/183/console
    FAILURE: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=metal-s390x/183/console
    FAILURE: https://jenkins.ubuntu.com/server/job/cloud-init-ci/nodes=vm-i386/183/console

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/183/rebuild

review: Needs Fixing (continuous-integration)

diff --git a/tools/ds-identify b/tools/ds-identify
index 3010634..54bd999 100755
--- a/tools/ds-identify
+++ b/tools/ds-identify
@@ -954,7 +954,9 @@ found() {
         shift
     fi
     # always write the None datasource last.
-    list="${list:+${list}, }None"
+    if [ "$list" != "None" ]; then
+        list="${list:+${list}, }None"
+    fi
     write_result "datasource_list: [ $list ]" "$@"
     return
 }