Merge ~paride/curtin:fix-deb-clean into curtin:master

[Paride Legovini]

deb packaging: fully cleanup directory tree after build

LP: #1899698

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

PASSED: Continuous integration, rev:a192a0b96acf042da12b7b791c14958aa386fdea
https://jenkins.ubuntu.com/server/job/curtin-ci/211/
Executed test runs:
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-amd64/211/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-arm64/211/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-ppc64el/211/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-s390x/211/

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/curtin-ci/211//rebuild

review: Approve (continuous-integration)

[Ryan Harper (raharper)]

LGTM

review: Approve

diff --git a/debian/clean b/debian/clean
new file mode 100644
index 0000000..51f3a0c
--- /dev/null
+++ b/debian/clean
@@ -0,0 +1,2 @@
+build/
+.coverage
diff --git a/debian/rules b/debian/rules
index 74be87c..c421771 100755
--- a/debian/rules
+++ b/debian/rules
@@ -20,3 +20,7 @@ override_dh_auto_install:
 
 override_dh_auto_test:
 	make unittest3
+
+override_dh_clean:
+	dh_clean
+	find . -name __pycache__ -exec rm -rf {} +