diff --git a/app/graphql/types/issue_type.rb b/app/graphql/types/issue_type.rb
index 432f3e1255f..4965601fe65 100644
--- a/app/graphql/types/issue_type.rb
+++ b/app/graphql/types/issue_type.rb
@@ -49,7 +49,6 @@ module Types
     field :web_url, GraphQL::STRING_TYPE, null: false # rubocop:disable Graphql/Descriptions
     field :relative_position, GraphQL::INT_TYPE, null: true # rubocop:disable Graphql/Descriptions
 
-    field :epic, ::Types::EpicType, null: true, description: 'The epic to which issue belongs'
     field :participants, Types::UserType.connection_type, null: true, complexity: 5, description: 'List of participants for the issue'
     field :time_estimate, GraphQL::INT_TYPE, null: false, description: 'The time estimate on the issue'
     field :total_time_spent, GraphQL::INT_TYPE, null: false, description: 'Total time reported as spent on the issue'
diff --git a/app/models/user.rb b/app/models/user.rb
index f5fbc912cc8..ad56d7a32c5 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -444,6 +444,7 @@ class User < ApplicationRecord
     #
     # Returns an ActiveRecord::Relation.
     def search(query)
+      query = query&.delete_prefix('@')
       return none if query.blank?
 
       query = query.downcase
diff --git a/changelogs/unreleased/allow-username-search-to-work-with-at-sign.yml b/changelogs/unreleased/allow-username-search-to-work-with-at-sign.yml
new file mode 100644
index 00000000000..fa6d679f7a2
--- /dev/null
+++ b/changelogs/unreleased/allow-username-search-to-work-with-at-sign.yml
@@ -0,0 +1,5 @@
+---
+title: Allow users to be searched with a @ prefix
+merge_request: 17742
+author:
+type: added
diff --git a/doc/ci/yaml/README.md b/doc/ci/yaml/README.md
index f45f23131c1..95b57421a6f 100644
--- a/doc/ci/yaml/README.md
+++ b/doc/ci/yaml/README.md
@@ -707,6 +707,7 @@ Available rule clauses include:
   (similar to [`only:variables`](#onlyvariablesexceptvariables)).
 - [`changes`](#ruleschanges)
   (same as [`only:changes`](#onlychangesexceptchanges)).
+- [`exists`](#rulesexists)
 
 For example, using `if`. This configuration specifies that `job` should be built
 and run for every pipeline on merge requests targeting `master`, regardless of
@@ -779,9 +780,42 @@ In this example, a job either set to:
 - Run manually if `Dockerfile` has changed OR `$VAR == "string value"`.
 - `when:on_success` by the last rule, where no earlier clauses evaluate to true.
 
+#### `rules:exists`
+
+`exists` accepts an array of paths and will match if any of these paths exist
+as files in the repository.
+
+For example:
+
+```yaml
+job:
+  script: docker build -t my-image:$CI_COMMIT_REF_SLUG .
+  rules:
+    - exists:
+      - Dockerfile
+```
+
+You can also use glob patterns to match multiple files in any directory within
+the repository.
+
+For example:
+
+```yaml
+job:
+  script: bundle exec rspec
+  rules:
+    - exists:
+      - spec/**.rb
+```
+
+NOTE: **Note:**
+For performance reasons, using `exists` with patterns is limited to 10000
+checks. After the 10000th check, rules with patterned globs will always match.
+
 #### Complex rule clauses
 
-To conjoin `if` and `changes` clauses with an AND, use them in the same rule.
+To conjoin `if`, `changes`, and `exists` clauses with an AND, use them in the
+same rule.
 
 In the following example:
 
@@ -805,6 +839,7 @@ The only clauses currently available are:
 
 - `if`
 - `changes`
+- `exists`
 
 Keywords such as `branches` or `refs` that are currently available for
 `only`/`except` are not yet available in `rules` as they are being individually
diff --git a/spec/graphql/types/issue_type_spec.rb b/spec/graphql/types/issue_type_spec.rb
index 1621319e618..59c42aa446d 100644
--- a/spec/graphql/types/issue_type_spec.rb
+++ b/spec/graphql/types/issue_type_spec.rb
@@ -10,7 +10,7 @@ describe GitlabSchema.types['Issue'] do
   it { expect(described_class.interfaces).to include(Types::Notes::NoteableType.to_graphql) }
 
   it 'has specific fields' do
-    fields = %i[iid title description state reference author assignees participants labels epic milestone due_date
+    fields = %i[iid title description state reference author assignees participants labels milestone due_date
                 confidential discussion_locked upvotes downvotes user_notes_count web_path web_url relative_position
                 time_estimate total_time_spent closed_at created_at updated_at task_completion_status]
 
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index a26b2979855..25e17f3bec4 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -1427,10 +1427,18 @@ describe User do
         expect(described_class.search(user.username)).to eq([user, user2])
       end
 
+      it 'returns users with a matching username starting with a @' do
+        expect(described_class.search("@#{user.username}")).to eq([user, user2])
+      end
+
       it 'returns users with a partially matching username' do
         expect(described_class.search(user.username[0..2])).to eq([user, user2])
       end
 
+      it 'returns users with a partially matching username starting with @' do
+        expect(described_class.search("@#{user.username[0..2]}")).to eq([user, user2])
+      end
+
       it 'returns users with a matching username regardless of the casing' do
         expect(described_class.search(user2.username.upcase)).to eq([user2])
       end