neomutt/signature: unset if disabled

Closes #2876

modules/programs/neomutt.nix

@@ -223,9 +223,11 @@ let
 
       # Extra configuration
       ${account.neomutt.extraConfig}
-    '' + optionalString (account.signature.showSignature != "none") ''
+    '' + (if (account.signature.showSignature == "none") then ''
+      unset signature
+    '' else ''
       set signature = ${pkgs.writeText "signature.txt" account.signature.text}
-    '' + optionalString account.notmuch.enable (notmuchSection account);
+    '') + optionalString account.notmuch.enable (notmuchSection account);
 
 in {
   options = {

tests/modules/programs/neomutt/hm-example.com-expected

@@ -31,6 +31,7 @@ set trash='+Trash'
 # Extra configuration
 color status cyan default
 
+unset signature
 # notmuch section
 set nm_default_uri = "notmuch:///home/hm-user/Mail"
 virtual-mailboxes "My INBOX" "notmuch://?query=tag:inbox"

tests/modules/programs/neomutt/hm-example.com-gpg-expected.conf

@@ -30,3 +30,4 @@ set trash='+Trash'
 
 # Extra configuration
 
+unset signature

tests/modules/programs/neomutt/hm-example.com-msmtp-expected.conf

@@ -30,3 +30,4 @@ set trash='+Trash'
 # Extra configuration
 color status cyan default
 
+unset signature

tests/modules/programs/neomutt/hm-example.com-no-folder-change-expected.conf

@@ -28,3 +28,4 @@ set trash='+Trash'
 
 # Extra configuration
 
+unset signature