Don't cache empty completions response at some locations

Eg. intelephense waits for 1 char before returning completions?
Fixes #745

plugin/completion.py

@@ -122,6 +122,11 @@ def is_same_completion(self, prefix: str, locations: 'List[int]') -> bool:
         if self.last_location < 0:
             return False
 
+        # issue 745, some servers return nothing until some chars into a word are returned
+        # Don't cache these empty responses.
+        if prefix and self.last_prefix == "" and not self.completions:
+            return False
+
         # completion requests from the same location with the same prefix are cached.
         current_start = locations[0] - len(prefix)
         last_start = self.last_location - len(self.last_prefix)

plugin/core/completion.py

@@ -70,8 +70,8 @@ def text_edit_text(item: dict, word_col: int) -> 'Optional[str]':
         if edit_range and edit_text:
             edit_range = Range.from_lsp(edit_range)
 
-            debug('textEdit from col {}, {} applied at col {}'.format(
-                edit_range.start.col, edit_range.end.col, word_col))
+            # debug('textEdit from col {}, {} applied at col {}'.format(
+            #     edit_range.start.col, edit_range.end.col, word_col))
 
             if edit_range.start.col <= word_col:
                 # if edit starts at current word, we can use it.