feat(openssl): openssl list -commands, not help

In scop#1256 we started parsing
the help output. Get the list instead from the `openssl list -commands`
command.

This also stops completing the encryption and digest algorithms, since
those are usually used with the `enc` and `dgst` subcommands.

Suggested-By: Michael Newton
Fixes: scop#1324

completions/openssl

@@ -27,6 +27,8 @@ _comp_cmd_openssl__compgen_sections()
 
 _comp_cmd_openssl__compgen_digests()
 {
+    #_comp_compgen -W "$($1 list  )"
+    #set -x
     [[ $cur == -* ]] || return
     _comp_compgen_split -- "$(
         "$1" dgst -h 2>&1 |
@@ -35,6 +37,7 @@ _comp_cmd_openssl__compgen_digests()
     _comp_compgen -ac "${cur#-}" split -P "-" -- "$("$1" help 2>&1 |
         command sed -ne '/^Message Digest commands/,/^[[:space:]]*$/p' |
         command sed -e 1d)"
+    set +x
 }
 
 _comp_cmd_openssl()
@@ -46,7 +49,7 @@ _comp_cmd_openssl()
 
     if ((cword == 1)); then
         local commands
-        commands="$("$1" help 2>&1 | command sed -e '/commands\|help:/d')"
+        commands="$("$1" list -commands)"
         _comp_compgen -- -W "$commands"
     else
         command=${words[1]}

test/t/test_openssl.py

@@ -5,9 +5,7 @@ class TestOpenssl:
     @pytest.mark.complete("openssl ", require_cmd=True)
     def test_1(self, completion):
         assert completion
-        assert all(
-            x in completion for x in "md5 x509 aes-128-cbc dgst pkey".split()
-        )
+        assert all(x in completion for x in "x509 dgst pkey enc".split())
 
     @pytest.mark.complete("openssl pkey -cipher ", require_cmd=True)
     def test_2(self, completion):