use "=" instead of ":" in displayin enum variant tags

Author: dr-orlovsky

rust/src/util.rs

@@ -124,7 +124,7 @@ impl Display for Variant {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         write!(f, "{}", self.name)?;
         if f.alternate() {
-            f.write_str(":")?;
+            f.write_str("=")?;
             Display::fmt(&self.tag, f)?;
         }
         Ok(())

rust/test_helpers/src/lib.rs

@@ -143,7 +143,7 @@ where T: Clone + PartialEq + Debug
     /// Test case failure representing failed byte string representation of the
     /// encoded enum variant
     #[display(
-        "Enum variant `{enum_name}:{variant_name}` has incorrect encoding:
+        "Enum variant `{enum_name}.{variant_name}` has incorrect encoding:
         \tExpected: {expected:02x?}
         \tActual: {actual:02x?}
         "