puppet: Fix puppet-apt bug with modern apt-key.

With modern apt-key, the fingerprints are displayed in the more fully
written-out format with spaces, and so `apt-key add` was being run
every time.

This fixes some unnecessary work being done on each puppet run on
Debian stretch.

I would have preferred to not need to do this by upgrading to
upstream, but see #7423 for notes on why that isn't going to work
(basically they broke support for puppet older than 4).

puppet/apt/manifests/key.pp

@@ -58,7 +58,7 @@ define apt::key (
         exec { $digest:
           command   => $digest_command,
           path      => '/bin:/usr/bin',
-          unless    => "/usr/bin/apt-key list | /bin/grep '${trimmedkey}'",
+          unless    => "/usr/bin/apt-key list | sed 's| ||g' | /bin/grep '${trimmedkey}'",
           logoutput => 'on_failure',
           before    => Anchor["apt::key ${upkey} present"],
         }
@@ -76,7 +76,7 @@ define apt::key (
       exec { "apt::key ${upkey} absent":
         command   => "apt-key del '${upkey}'",
         path      => '/bin:/usr/bin',
-        onlyif    => "apt-key list | grep '${trimmedkey}'",
+        onlyif    => "apt-key list | sed 's| ||g' | grep '${trimmedkey}'",
         user      => 'root',
         group     => 'root',
         logoutput => 'on_failure',