Merge branch 'alpinefix' into 'master'

Fix for alpine "getent shadow" missing functionality in __user type

See merge request !855

cdist/conf/type/__user/explorer/shadow

@@ -24,7 +24,7 @@
 name=$__object_id
 
 case $("$__explorer/os") in
-  'freebsd'|'netbsd'|'openbsd')
+  'freebsd'|'netbsd'|'openbsd'|'alpine')
     database='passwd'
     ;;
   # Default to using shadow passwords