Hide collapse icon in diff with no lines (#21094)

Sometimes (e.g. renaming a file) nothing of the content is changed. In
this case, it makes no sense to show the collapse icon in a diff.

Author: JakobDev

templates/repo/diff/box.tmpl

@@ -79,13 +79,15 @@
 						<div class="diff-file-box diff-box file-content {{TabSizeClass $.Editorconfig $file.Name}} mt-3" id="diff-{{$file.NameHash}}" data-old-filename="{{$file.OldName}}" data-new-filename="{{$file.Name}}" {{if $file.ShouldBeHidden}}data-folded="true"{{end}}>
 							<h4 class="diff-file-header sticky-2nd-row ui top attached normal header df ac sb">
 								<div class="df ac">
-									<a role="button" class="fold-file muted mr-2">
-										{{if $file.ShouldBeHidden}}
-											{{svg "octicon-chevron-right" 18}}
-										{{else}}
-											{{svg "octicon-chevron-down" 18}}
-										{{end}}
-									</a>
+									{{if or (gt $file.Addition 0) (gt $file.Deletion 0) $file.IsBin}}
+										<a role="button" class="fold-file muted mr-2">
+											{{if $file.ShouldBeHidden}}
+												{{svg "octicon-chevron-right" 18}}
+											{{else}}
+												{{svg "octicon-chevron-down" 18}}
+											{{end}}
+										</a>
+									{{end}}
 									<div class="bold df ac">
 										{{if $file.IsBin}}
 											<span class="ml-1 mr-3">