Version gate changes to expr::shape_from_rhs_tactic

Although the issue described in 5321 could be considered a bug, it might
also lead to breaking formatting changes. For that reason the fix is
only applied when `version=Two`

Author: ytmimi

Diff for: src/expr.rs

@@ -2110,8 +2110,10 @@ fn shape_from_rhs_tactic(
     shape: Shape,
     rhs_tactic: RhsTactics,
 ) -> Option<Shape> {
+    let using_version_2 = context.config.version() == Version::Two;
+    let no_indent = shape.indent.width() == 0;
     match rhs_tactic {
-        RhsTactics::ForceNextLineWithoutIndent if shape.indent.width() == 0 => shape
+        RhsTactics::ForceNextLineWithoutIndent if no_indent && using_version_2 => shape
             .with_max_width(context.config)
             .sub_width(context.config.tab_spaces()),
         RhsTactics::ForceNextLineWithoutIndent => shape

Diff for: tests/source/issue_5321.rs

@@ -1,3 +1,5 @@
+// rustfmt-version: Two
+
 trait AllTheOthers1: Trait3 + Trait4 + Trait5 + Trait6 + Trait7 + Trait8 + Trait9 + Trait10 + Trait11 + Trait12 + Trait14
 {
 }

Diff for: tests/target/issue_5321.rs

@@ -1,3 +1,5 @@
+// rustfmt-version: Two
+
 trait AllTheOthers1:
     Trait3
     + Trait4