Do not load mathrsfs if unicode-math is required (#12734)

The latter provides \mathscr and the packages clash

(cherry picked from commit a15bc829d1)

src/mathed/InsetMathFont.cpp

@@ -128,7 +128,7 @@ void InsetMathFont::validate(LaTeXFeatures & features) const
 		if (fontname == "text" || fontname == "textnormal"
 		    || (fontname.length() == 6 && fontname.substr(0, 4) == "text"))
 			features.require("amstext");
-		if (fontname == "mathscr")
+		if (fontname == "mathscr" && !features.isRequired("unicode-math"))
 			features.require("mathrsfs");
 		if (fontname == "textipa")
 			features.require("tipa");

status.23x

@@ -43,6 +43,8 @@ What's new
 
 - Fix leaking of linespace settings between paragraphs if they have
   different aligment (bug 12638).
+  
+- Do not load mathrsfs if unicode-math is required (bug 12734).
 
 
 * USER INTERFACE