fix substitution losing track of document range (#1547)

esphome/components/substitutions/__init__.py

@@ -4,6 +4,7 @@ import re
 import esphome.config_validation as cv
 from esphome import core
 from esphome.const import CONF_SUBSTITUTIONS
+from esphome.yaml_util import ESPHomeDataBase, make_data_base
 
 CODEOWNERS = ['@esphome/core']
 _LOGGER = logging.getLogger(__name__)
@@ -68,6 +69,14 @@ def _expand_substitutions(substitutions, value, path):
         value = value[:i] + sub
         i = len(value)
         value += tail
+
+    # orig_value can also already be a lambda with esp_range info, and only
+    # a plain string is sent in orig_value
+    if isinstance(orig_value, ESPHomeDataBase):
+        # even though string can get larger or smaller, the range should point
+        # to original document marks
+        return make_data_base(value, orig_value)
+
     return value