Merge ~mwhudson/curtin:swap-exit into curtin:master

[Michael Hudson-Doyle]

fix "curtin swap" exit code

Today I discovered that there is a "curtin swap" command that just does
the "configure swap" part of curthooks and then I fairly quickly after
that discovered that probably noone has used it because it
unconditionally exits with code 2 even if everything succeeded.

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

PASSED: Continuous integration, rev:9ccf75c478e96802da41c2e4392c093bff7e2474
https://jenkins.canonical.com/server-team/job/curtin-ci/57/
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    SUCCESS: https://jenkins.canonical.com/server-team/job/curtin-ci/nodes=metal-ppc64el/57/
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review: Approve (continuous-integration)

[Dan Bungert (dbungert)]

review: Approve

diff --git a/curtin/commands/swap.py b/curtin/commands/swap.py
index 089cd73..a5082ac 100644
--- a/curtin/commands/swap.py
+++ b/curtin/commands/swap.py
@@ -41,7 +41,7 @@ def swap_main(args):
     swap.setup_swapfile(target=state['target'], fstab=state['fstab'],
                         swapfile=args.swapfile, size=size,
                         maxsize=args.maxsize, force=args.force)
-    sys.exit(2)
+    sys.exit(0)
 
 
 CMD_ARGUMENTS = (