[MM-63597] Fix From: autocompletion (#30673)

webapp/channels/src/components/new_search/search_box.tsx

@@ -170,7 +170,7 @@ const SearchBox = forwardRef(
                 }
 
                 setSearchTerms(
-                    searchTerms.slice(0, caretPosition).replace(new RegExp(escapedMatchedPretext + '$', 'i'), '') +
+                    searchTerms.slice(0, caretPosition).replace(new RegExp(escapedMatchedPretext + '$', 'i'), '').trimEnd() +
                     val +
                     extraSpace +
                     searchTerms.slice(caretPosition),
@@ -228,7 +228,8 @@ const SearchBox = forwardRef(
         const changeSearchTeam = (selectedTeam: string) => {
             const newTerms = searchTerms.
                 replace(/\bin:[^\s]*/gi, '').replace(/\s{2,}/g, ' ').
-                replace(/\bfrom:[^\s]*/gi, '').replace(/\s{2,}/g, ' ');
+                replace(/\bfrom:[^\s]*/gi, '').replace(/\s{2,}/g, ' ').
+                trim();
 
             if (newTerms !== searchTerms) {
                 clearTimeout(filterResetTimeout.current);

webapp/channels/src/components/suggestion/search_user_provider.tsx

@@ -71,6 +71,11 @@ export default class SearchUserProvider extends Provider {
     }
 
     handlePretextChanged(pretext: string, resultsCallback: ResultsCallback<UserProfile>, teamId: string) {
+        // no autocomplete on All teams
+        if (teamId === '') {
+            return false;
+        }
+
         const captured = (/\bfrom:\s*(\S*)$/i).exec(pretext.toLowerCase());
 
         this.doAutocomplete(captured, teamId, resultsCallback);