Update documentation of colors on Status.

site/dev/testing/buildbot.md

Index: site/dev/testing/buildbot.md
diff --git a/site/dev/testing/buildbot.md b/site/dev/testing/buildbot.md
index 2f4a12fb532e651bfda4798fc5f6a88d6c38c433..941aadd7c35ac5e75900e95bfbbbc7b3e12ad1b7 100644
--- a/site/dev/testing/buildbot.md
+++ b/site/dev/testing/buildbot.md
@@ -70,10 +70,16 @@ Status View
 
 The status view shows a table with builders, grouped by test type and platform,
 on the X-axis and commits on the Y-axis.  The cells are colored according to
-the status of the build for each commit: green indicates success, red indicates
-failure, light orange indicates an in-progress build, and white indicates that
-no build has started yet for a given revision. Commits are listed by author, and
-the branch on which the commit was made is shown on the very left.
+the status of the build for each commit:
+
+* green: success
+* orange: failure
+* purple: exception (infrastructure issue)
+* black border, no fill: build in progress
+* blank: no build has started yet for a given revision
+
+Commits are listed by author, and the branch on which the commit was made is
+shown on the very left. A purple result will override an orange result.
 
 For more detail, you can click on an individual cell to get a summary of the
 steps which ran for that build.  You can also click one of the white bars at