rebaseline.py: error out early if --expectations-root not pointing at gm-expected dir

tools/tests/run.sh

 #!/bin/bash
 
 # Tests for our tools.
 #
 # TODO: currently, this only passes on Linux (which is the platform that
 # the housekeeper bot runs on, e.g.
 # http://70.32.156.51:10117/builders/Skia_PerCommit_House_Keeping/builds/1415/steps/RunToolSelfTests/logs/stdio )
 # See https://code.google.com/p/skia/issues/detail?id=677
 # ('make tools/tests/run.sh work cross-platform')
 # Ideally, these tests should pass on all development platforms...
@@ skipping 249 matching lines @@
 fi
 
 #
 # Test rebaseline.py ...
 #
 
 REBASELINE_INPUT=tools/tests/rebaseline/input
 REBASELINE_OUTPUT=tools/tests/rebaseline/output
 
 # These test the old image-file expectations.
-rebaseline_images_test "--expectations-root fake/expectations/path --actuals-base-url file:$REBASELINE_INPUT/json1 --tests nonexistenttest1 imageblur nonexistenttest2 --configs nonexistentconfig1 8888 nonexistentconfig2 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float" "$REBASELINE_OUTPUT/subset"
-rebaseline_images_test "--actuals-base-url file:$REBASELINE_INPUT/json1 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float" "$REBASELINE_OUTPUT/using-json1"
-rebaseline_images_test "--actuals-base-url file:$REBASELINE_INPUT/json1 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float --add-new" "$REBASELINE_OUTPUT/using-json1-add-new"
+rebaseline_images_test "--expectations-root $REBASELINE_INPUT/fake-gm-expected-dir --actuals-base-url file:$REBASELINE_INPUT/json1 --tests nonexistenttest1 imageblur nonexistenttest2 --configs nonexistentconfig1 8888 nonexistentconfig2 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float" "$REBASELINE_OUTPUT/subset"
+rebaseline_images_test "--expectations-root $REBASELINE_INPUT/fake-gm-expected-dir --actuals-base-url file:$REBASELINE_INPUT/json1 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float" "$REBASELINE_OUTPUT/using-json1"
+rebaseline_images_test "--expectations-root $REBASELINE_INPUT/fake-gm-expected-dir --actuals-base-url file:$REBASELINE_INPUT/json1 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float --add-new" "$REBASELINE_OUTPUT/using-json1-add-new"
+rebaseline_images_test "--expectations-root $REBASELINE_INPUT --actuals-base-url file:$REBASELINE_INPUT/json1 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float" "$REBASELINE_OUTPUT/exercise-bug1403"
 
 # These test the new JSON-format expectations.
 rebaseline_test "$REBASELINE_INPUT/json1" "--actuals-base-url $REBASELINE_INPUT/json1 --subdirs base-android-galaxy-nexus base-shuttle-win7-intel-float" "$REBASELINE_OUTPUT/using-json1-expectations"
 
 #
 # Test jsondiff.py ...
 #
 
 JSONDIFF_INPUT=tools/tests/jsondiff/input
 JSONDIFF_OUTPUT=tools/tests/jsondiff/output
 jsondiff_test "$JSONDIFF_INPUT/old.json $JSONDIFF_INPUT/new.json" "$JSONDIFF_OUTPUT/old-vs-new"
 
 
 echo "All tests passed."