Avoid exceptions when analyzing truncated test output.
Avoid exceptions when analyzing truncated test output.

r34867 introduced a mechanism to truncate excessively long test
output.  Since the truncation may happen in the middle of a line, we
need to be tolerant of mal-formed lines when analyzing the test
output.

R=kustermann@google.com, whesse@google.com

Review URL: https://codereview.chromium.org//236313005

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@35063 260f80e4-7a28-3924-810f-c04153c831b5

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