patch 7.4.1931
Problem:    Using both old and new style file mark lines from viminfo.
Solution:   Skip the old style lines if the viminfo file was written with a
            Vim version that supports the new style.
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 519f40c..ec405cb 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -2310,7 +2310,11 @@
 		break;
 	    case '-':
 	    case '\'':
-		eof = read_viminfo_filemark(virp, forceit);
+		/* When file marks are in bar lines skip the old style lines. */
+		if (virp->vir_version < VIMINFO_VERSION_WITH_MARKS)
+		    eof = read_viminfo_filemark(virp, forceit);
+		else
+		    eof = viminfo_readline(virp);
 		break;
 	    default:
 		if (viminfo_error("E575: ", _("Illegal starting char"),