Use partials instead of simple switch case:

app/views/notify/ci/builds/_build.html.haml

+%a{href: pipeline_build_url(pipeline, build), style: "color:#3777b0;text-decoration:none;"}
+  = build.name

app/views/notify/ci/builds/_build.text.erb

+Build #<%= build.id %> ( <%= pipeline_build_url(@pipeline, build) %> )

app/views/notify/generic_commit_statuses/_generic_commit_status.html.haml

+= build.name

app/views/notify/generic_commit_statuses/_generic_commit_status.text.erb

+Build #<%= build.id %>

app/views/notify/pipeline_failed_email.html.haml

@@ -158,12 +158,7 @@
                                             %td{style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;color:#8c8c8c;font-weight:500;font-size:15px;vertical-align:middle;"}
                                               = build.stage
                                     %td{align: "right", style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;padding:20px 0;color:#8c8c8c;font-weight:500;font-size:15px;"}
-                                      - case build
-                                      - when Ci::Build
-                                        %a{href: pipeline_build_url(@pipeline, build), style: "color:#3777b0;text-decoration:none;"}
-                                          = build.name
-                                      - when GenericCommitStatus
-                                        = build.name
+                                      = render "notify/#{build.to_partial_path}", pipeline: @pipeline, build: build
                                   %tr.build-log
                                     - if build.has_trace?
                                       %td{colspan: "2", style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;padding:0 0 15px;"}

app/views/notify/pipeline_failed_email.text.erb

@@ -19,7 +19,7 @@ Commit Author: <%= commit.author_name %>
 Pipeline #<%= @pipeline.id %> ( <%= pipeline_url(@pipeline) %> ) had <%= failed.size %> failed <%= 'build'.pluralize(failed.size) %>.
 
 <% failed.each do |build| -%>
-Build #<%= build.id %><%= if build.kind_of?(Ci::Build) then " ( #{pipeline_build_url(@pipeline, build)} )" end %>
+<%= render "notify/#{build.to_partial_path}", pipeline: @pipeline, build: build %>
 Stage: <%= build.stage %>
 Name: <%= build.name %>
 <% if build.has_trace? -%>