Added test for obsolete bug and removed workaround in code.

compiler/testData/diagnostics/tests/overload/kt2493.kt

@@ -0,0 +1,19 @@
+trait A
+trait B
+
+fun <R: A> R.f() {
+}
+
+fun <R: B> R.f() {
+}
+
+class AImpl: A
+class BImpl: B
+
+class C: A, B
+
+fun main(args: Array<String>) {
+    AImpl().f()
+    BImpl().f()
+    C().<!CANNOT_COMPLETE_RESOLVE!>f<!>()
+}

compiler/testData/diagnostics/tests/overload/kt2493.txt

@@ -0,0 +1,38 @@
+package
+
+internal fun main(/*0*/ args: kotlin.Array<kotlin.String>): kotlin.Unit
+internal fun </*0*/ R : A> R.f(): kotlin.Unit
+internal fun </*0*/ R : B> R.f(): kotlin.Unit
+
+internal trait A {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal final class AImpl : A {
+    public constructor AImpl()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal trait B {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal final class BImpl : B {
+    public constructor BImpl()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal final class C : A, B {
+    public constructor C()
+    public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+}