don't force print the prompt when reading a line with the ConsoleHandler

(cherry picked from commit 0bd4d9c)

Author: timfel

graalpython/com.oracle.graal.python.shell/src/com/oracle/graal/python/shell/ConsoleHandler.java

@@ -63,7 +63,11 @@ public abstract class ConsoleHandler {
     /**
      * Read a line of input, newline is <b>NOT</b> included in result.
      */
-    public abstract String readLine();
+    public final String readLine() {
+        return readLine(true);
+    }
+
+    public abstract String readLine(boolean prompt);
 
     public abstract void setPrompt(String prompt);
 
@@ -90,7 +94,7 @@ public InputStream createInputStream() {
             public int read() throws IOException {
                 if (buffer == null) {
                     pos = 0;
-                    String line = readLine();
+                    String line = readLine(false);
                     if (line == null) {
                         return -1;
                     }

graalpython/com.oracle.graal.python.shell/src/com/oracle/graal/python/shell/DefaultConsoleHandler.java

@@ -59,9 +59,9 @@ public DefaultConsoleHandler(InputStream in, OutputStream out) {
     }
 
     @Override
-    public String readLine() {
+    public String readLine(boolean showPrompt) {
         try {
-            if (prompt != null) {
+            if (prompt != null && showPrompt) {
                 out.print(prompt);
             }
             return in.readLine();

graalpython/com.oracle.graal.python.shell/src/com/oracle/graal/python/shell/JLineConsoleHandler.java

@@ -237,10 +237,10 @@ public void setContext(Context context) {
     }
 
     @Override
-    public String readLine() {
+    public String readLine(boolean showPrompt) {
         try {
             console.getTerminal().init();
-            return console.readLine();
+            return console.readLine(showPrompt ? console.getPrompt() : "");
         } catch (UserInterruptException e) {
             throw e;
         } catch (Exception ex) {