git: apply sendmailCmd instead of smtpServer (#6399)

In manpage of git-send-email --smtp-server,

    For backward compatibility, this option can also specify
    full pathname of a sendmail-like program instead; the program
    must support the -i option. This method does not support
    passing arguments or using plain command names. For those use
    cases, consider using --sendmail-cmd instead.

modules/programs/git.nix

@@ -489,7 +489,7 @@ in {
         genIdentity = name: account:
           with account;
           nameValuePair "sendemail.${name}" (if account.msmtp.enable then {
-            smtpServer = "${pkgs.msmtp}/bin/msmtp";
+            sendmailCmd = "${pkgs.msmtp}/bin/msmtp";
             envelopeSender = "auto";
             from = "${realName} <${address}>";
           } else

tests/modules/programs/git/git-with-msmtp-expected.conf

@@ -14,7 +14,7 @@
 [sendemail "[email protected]"]
 	envelopeSender = "auto"
 	from = "H. M. Test <[email protected]>"
-	smtpServer = "@msmtp@/bin/msmtp"
+	sendmailCmd = "@msmtp@/bin/msmtp"
 
 [user]
 	email = "[email protected]"

tests/modules/programs/git/git-with-msmtp.nix

@@ -31,7 +31,7 @@
 
     assertGitConfig "[email protected]" "H. M. Test <[email protected]>"
     assertGitConfig "sendemail.hm-account.from" "H. M. Test Jr. <[email protected]>"
-    assertGitConfig "[email protected].smtpServer" "${pkgs.msmtp}/bin/msmtp"
+    assertGitConfig "[email protected].sendmailCmd" "${pkgs.msmtp}/bin/msmtp"
     assertGitConfig "[email protected]" "auto"
   '';
 }