Put hyphen at the end of group expression

plugins/common/functions

@@ -1065,7 +1065,7 @@ strip_inline_comments() {
 
 is_valid_hostname() {
   declare desc="return 0 if argument is a valid hostname; else return 1"
-  local hostname_string="${1,,}"; local hostname_regex='^([a-z0-9\-\*]+\.)*[a-z0-9\-\*]+$'
+  local hostname_string="${1,,}"; local hostname_regex='^([a-z0-9\*-]+\.)*[a-z0-9\*-]+$'
   if [[ $hostname_string =~ $hostname_regex ]]; then
     return 0
   else

tests/unit/20_domains.bats

@@ -35,6 +35,10 @@ teardown() {
   echo "output: "$output
   echo "status: "$status
   assert_success
+  run dokku domains:add $TEST_APP a--domain.with--hyphens
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
 }
 
 @test "(domains) domains:add (multiple)" {