[FIX] qweb: t-set with a body should not be joined with comma

closes #574

src/qweb/qweb.ts

@@ -119,7 +119,7 @@ const UTILS: Utils = {
           return vnode.text;
         }
       })
-      .join();
+      .join("");
   },
   getComponent(obj) {
     while (obj && !obj.hasOwnProperty("__owl__")) {

tests/qweb/__snapshots__/qweb.test.ts.snap

@@ -2965,6 +2965,33 @@ exports[`t-set t-set should reuse variable if possible 1`] = `
 }"
 `;
 
+exports[`t-set t-set with content and sub t-esc 1`] = `
+"function anonymous(context, extra
+) {
+    // Template name: \\"test\\"
+    let utils = this.constructor.utils;
+    let scope = Object.create(context);
+    let h = this.h;
+    let c1 = [], p1 = {key:1};
+    let vn1 = h('div', p1, c1);
+    let c2 = new utils.VDomArray();
+    let _3 = scope['beep'];
+    if (_3 != null) {
+        c2.push({text: _3});
+    }
+    c2.push({text: \` boop\`});
+    scope.setvar = c2
+    if (scope.setvar != null) {
+        let _origScope4 = scope;
+        scope = Object.assign(Object.create(context), scope);
+        scope.setvar = scope.setvar instanceof utils.VDomArray ? utils.vDomToString(scope.setvar) : scope.setvar;
+        c1.push({text: scope.setvar});
+        scope = _origScope4;
+    }
+    return vn1;
+}"
+`;
+
 exports[`t-set t-set with t-value (falsy) and body 1`] = `
 "function anonymous(context, extra
 ) {

tests/qweb/qweb.test.ts

@@ -154,24 +154,28 @@ describe("t-esc", () => {
   });
 
   test("div with falsy values", () => {
-    qweb.addTemplate("test", `
+    qweb.addTemplate(
+      "test",
+      `
       <div>
         <p t-esc="v1"/>
         <p t-esc="v2"/>
         <p t-esc="v3"/>
         <p t-esc="v4"/>
         <p t-esc="v5"/>
-      </div>`);
+      </div>`
+    );
     const vals = {
       v1: false,
       v2: undefined,
       v3: null,
       v4: 0,
       v5: ""
-    }
-    expect(renderToString(qweb, "test", vals)).toBe("<div><p>false</p><p></p><p></p><p>0</p><p></p></div>");
+    };
+    expect(renderToString(qweb, "test", vals)).toBe(
+      "<div><p>false</p><p></p><p></p><p>0</p><p></p></div>"
+    );
   });
-
 });
 
 describe("t-raw", () => {
@@ -278,6 +282,18 @@ describe("t-set", () => {
     );
   });
 
+  test("t-set with content and sub t-esc", () => {
+    qweb.addTemplate(
+      "test",
+      `<div>
+        <t t-set="setvar"><t t-esc="beep"/> boop</t>
+        <t t-esc="setvar"/>
+      </div>`
+    );
+
+    expect(renderToString(qweb, "test", { beep: "beep" })).toBe("<div>beep boop</div>");
+  });
+
   test("evaluate value expression, part 2", () => {
     qweb.addTemplate(
       "test",