hmm one more hairlines 'straggler' might be flipflopping

expectations/gm/Test-Win7-ShuttleA-HD2000-x86-Debug/expected-results.json

 {
   "actual-results": {
     "failed": null, 
     "failure-ignored": null, 
     "no-comparison": null, 
     "succeeded": null
   }, 
   "expected-results": {
     "3x3bitmaprect_565.png": {
       "allowed-digests": [
@@ skipping 8354 matching lines @@
           "bitmap-64bitMD5", 
           4408059671304210250
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "hairlines_gpu.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
-          4524273330023826834
+          14068005127069681159
         ]
       ], 
       "reviewed-by-human": true
     }, 
     "hairlines_pdf-poppler.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           977372539310569340
         ]
@@ skipping 5833 matching lines @@
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           12937422788648264516
         ]
       ], 
       "reviewed-by-human": true
     }
   }
 }