Only add an indentation level for colons at end of line

Closes codemirror#6634

Author: marijnh

mode/python/python.js

@@ -318,7 +318,7 @@
         state.dedent += 1;
 
       if (current == "lambda") state.lambda = true;
-      if (current == ":" && !state.lambda && top(state).type == "py")
+      if (current == ":" && !state.lambda && top(state).type == "py" && stream.match(/^\s*(?:#|$)/, false))
         pushPyScope(state);
 
       if (current.length == 1 && !/string|comment/.test(style)) {

mode/python/test.js

@@ -41,4 +41,8 @@
   MT("bracesInFString", "[string f']{[variable x] [operator +] {}}[string !']")
 
   MT("nestedFString", "[string f']{[variable b][[ [string f\"c\"] ]]}[string f'] [comment # oops]")
+
+  MT("dontIndentTypeDecl",
+     "[variable i]: [builtin int] [operator =] [number 32]",
+     "[builtin print]([variable i])")
 })();