[CONJ-1035] correcting double write of buffer when writing ascii data…

… in case of growing packet buffer

src/main/java/org/mariadb/jdbc/client/socket/impl/PacketWriter.java

@@ -347,6 +347,7 @@ public void writeAscii(String str) throws IOException {
     if (len > buf.length - pos) {
       byte[] arr = str.getBytes(StandardCharsets.US_ASCII);
       writeBytes(arr, 0, arr.length);
+      return;
     }
     for (int off = 0; off < len; ) {
       this.buf[this.pos++] = (byte) str.charAt(off++);

src/test/java/org/mariadb/jdbc/unit/client/socket/PackerWriterTest.java

@@ -0,0 +1,25 @@
+package org.mariadb.jdbc.unit.client.socket;
+
+import java.io.IOException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.mariadb.jdbc.client.socket.impl.PacketWriter;
+
+public class PackerWriterTest {
+
+  @Test
+  public void growBuffer() throws IOException {
+    PacketWriter pw = new PacketWriter(null, 0, 0xffffff, null, null);
+    Assertions.assertEquals(4, pw.pos());
+    pw.writeBytes(new byte[8190], 0, 8190);
+    pw.writeAscii("abcdefghij");
+    Assertions.assertEquals(8200, pw.pos() - 4);
+
+    for (int i = 0; i < 8190; i++) {
+      Assertions.assertEquals(0, pw.buf()[i + 4]);
+    }
+    for (int i = 0; i < 10; i++) {
+      Assertions.assertEquals('a' + i, pw.buf()[i + 8194]);
+    }
+  }
+}