Merge commit '4896d2c4c6d3bd6b878c5a075b6611c65d4203b2' into glitch-soc/merge-upstream

Conflicts:
- `app/views/settings/preferences/appearance/show.html.haml`:
  Upstream changed stuff too close to glitch-soc's theming system changes.
  Applied upstream's changes.
- `streaming/index.js`:
  Upstream refactored a bunch of stuff where our code was different due to
  local-only posts.
  Applied upstream's changes while taking care of local-only posts.

app/javascript/mastodon/actions/compose.js

@@ -624,6 +624,7 @@ export function fetchComposeSuggestions(token) {
       fetchComposeSuggestionsEmojis(dispatch, getState, token);
       break;
     case '#':
+    case '＃':
       fetchComposeSuggestionsTags(dispatch, getState, token);
       break;
     default:
@@ -665,11 +666,11 @@ export function selectComposeSuggestion(position, token, suggestion, path) {
 
       dispatch(useEmoji(suggestion));
     } else if (suggestion.type === 'hashtag') {
-      completion    = `#${suggestion.name}`;
-      startPosition = position - 1;
+      completion    = suggestion.name.slice(token.length - 1);
+      startPosition = position + token.length;
     } else if (suggestion.type === 'account') {
-      completion    = getState().getIn(['accounts', suggestion.id, 'acct']);
-      startPosition = position;
+      completion    = `@${getState().getIn(['accounts', suggestion.id, 'acct'])}`;
+      startPosition = position - 1;
     }
 
     // We don't want to replace hashtags that vary only in case due to accessibility, but we need to fire off an event so that
@@ -729,7 +730,7 @@ function insertIntoTagHistory(recognizedTags, text) {
     // complicated because of new normalization rules, it's no longer just
     // a case sensitivity issue
     const names = recognizedTags.map(tag => {
-      const matches = text.match(new RegExp(`#${tag.name}`, 'i'));
+      const matches = text.match(new RegExp(`[#＃]${tag.name}`, 'i'));
 
       if (matches && matches.length > 0) {
         return matches[0].slice(1);