make ignored-tests.txt specify full test name, not partial name

gm/tests/outputs/ignoring-one-test/output-expected/json-summary.txt

 {
    "actual-results" : {
       "failed" : {
-         "565/selftest1.png" : [ "bitmap-64bitMD5", 12927999507540085554 ]
+         "565/selftest2.png" : [ "bitmap-64bitMD5", 8863920166200910451 ],
+         "8888/selftest2.png" : [ "bitmap-64bitMD5", 13451349865803053525 ]
       },
       "failure-ignored" : {
+         "565/selftest1.png" : [ "bitmap-64bitMD5", 12927999507540085554 ],
          "8888/selftest1.png" : [ "bitmap-64bitMD5", 1209453360120438698 ]
       },
       "no-comparison" : null,
       "succeeded" : null
    },
    "expected-results" : {
       "565/selftest1.png" : {
          "allowed-digests" : [
             [ "bitmap-64bitMD5", 8863920166200910451 ]
          ],
+         "ignore-failure" : true
+      },
+      "565/selftest2.png" : {
+         "allowed-digests" : [
+            [ "bitmap-64bitMD5", 12927999507540085554 ]
+         ],
          "ignore-failure" : false
       },
       "8888/selftest1.png" : {
          "allowed-digests" : [
             [ "bitmap-64bitMD5", 13451349865803053525 ]
          ],
          "ignore-failure" : true
+      },
+      "8888/selftest2.png" : {
+         "allowed-digests" : [
+            [ "bitmap-64bitMD5", 1209453360120438698 ]
+         ],
+         "ignore-failure" : false
       }
    }
 }