restore space in Python line comment prefix (PY-10929); re-fix PY-9840 correctly

platform/lang-impl/src/com/intellij/codeInsight/editorActions/enter/EnterInLineCommentHandler.java

@@ -48,6 +48,7 @@ public class EnterInLineCommentHandler extends EnterHandlerDelegateAdapter {
         if (offset < document.getTextLength() && text.charAt(offset) != '\n') {
           String prefix = commenter.getLineCommentPrefix();
           assert prefix != null: "Line Comment type is set but Line Comment Prefix is null!";
+          prefix = prefix.trim();
           if (!StringUtil.startsWith(text, offset, prefix)) {
             if (text.charAt(caretOffset) != ' ' && !prefix.endsWith(" ")) {
               prefix += " ";

python/src/com/jetbrains/python/PythonCommenter.java

@@ -26,7 +26,7 @@ import org.jetbrains.annotations.Nullable;
  */
 public class PythonCommenter implements CodeDocumentationAwareCommenter, IndentedCommenter {
   public String getLineCommentPrefix() {
-    return "#";
+    return "# ";
   }
 
   public String getBlockCommentPrefix() {

python/testData/commenter/indentedComment_after.py

@@ -1,3 +1,3 @@
 def foo():
-    #i = 1
+    # i = 1
     j = 2

python/testData/inspections/suppress/suppressForStatement.after.py

@@ -1,2 +1,2 @@
-#noinspection PyUnresolvedReferences
+# noinspection PyUnresolvedReferences
 print x<caret>xx