Make sure that exception recovery does not break exception message

Fixes #1631

Author: elizarov

kotlinx-coroutines-core/jvm/src/internal/StackTraceRecovery.kt

@@ -66,14 +66,15 @@ private fun <E : Throwable> recoverFromStackFrame(exception: E, continuation: Co
 
     // Try to create an exception of the same type and get stacktrace from continuation
     val newException = tryCopyException(cause) ?: return exception
+    // Verify that the new exception has the same message as the original one (bail out if not, see #1631)
+    if (newException.message != cause.message) return exception
+    // Update stacktrace
     val stacktrace = createStackTrace(continuation)
     if (stacktrace.isEmpty()) return exception
-
     // Merge if necessary
     if (cause !== exception) {
         mergeRecoveredTraces(recoveredStacktrace, stacktrace)
     }
-
     // Take recovered stacktrace, merge it with existing one if necessary and return
     return createFinalException(cause, newException, stacktrace)
 }

kotlinx-coroutines-core/jvm/test/exceptions/StackTraceRecoveryTest.kt

@@ -8,6 +8,7 @@ import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.*
 import kotlinx.coroutines.intrinsics.*
 import org.junit.Test
+import java.lang.RuntimeException
 import java.util.concurrent.*
 import kotlin.concurrent.*
 import kotlin.coroutines.*
@@ -264,4 +265,18 @@ class StackTraceRecoveryTest : TestBase() {
         }
         yield() // nop to make sure it is not a tail call
     }
+
+    @Test
+    fun testWrongMessageException() = runTest {
+        val result = runCatching {
+            coroutineScope<Unit> {
+                throw WrongMessageException("OK")
+            }
+        }
+        val ex = result.exceptionOrNull() ?: error("Expected to fail")
+        assertTrue(ex is WrongMessageException)
+        assertEquals("Token OK", ex.message)
+    }
+
+    public class WrongMessageException(token: String) : RuntimeException("Token $token")
 }