Fix test tag parsing to split [.foo] into [.][foo]

include/internal/catch_test_case_info.cpp

@@ -75,6 +75,12 @@ namespace Catch {
                     else if( prop == TestCaseInfo::None )
                         enforceNotReservedTag( tag, _lineInfo );
 
+                    // Merged hide tags like `[.approvals]` should be added as
+                    // `[.][approvals]`. The `[.]` is added at later point, so
+                    // we only strip the prefix
+                    if (startsWith(tag, '.') && tag.size() > 1) {
+                        tag.erase(0, 1);
+                    }
                     tags.push_back( tag );
                     tag.clear();
                     inTag = false;