generate_workspace is generating invalid shas

[petroseskinder]

Migrated from issue #1131 in original repository.

generate_workspace seems to be creating invalid sha1 entries of the form:

maven_jar(
    name = "net_java_dev_jets3t_jets3t",
    artifact = "net.java.dev.jets3t:jets3t:0.6.1",
    sha1 = "9f95b944ccbbbeedd397e8f62e5690fd735a45e5  maven2/net/java/dev/jets3t/jets3t/0.6.1/jets3t-0.6.1.jar",
)

I'm currently synced to 653869e (HEAD~1 because HEAD seems to be broken).

It's including the rest of the .sha1 file it downloaded, not cutting it off after the sha. See https://groups.google.com/d/msg/bazel-discuss/gu8RbSdD0xY/YvI3f9azAQAJ.

One potential cause: https://github.com/bazelbuild/bazel/blob/master/src/tools/generate_workspace/src/main/java/com/google/devtools/build/workspace/maven/Resolver.java#L275?

[qibinlou]

To add one invalid case, I got something like sha1 = "html", which seems to be also relevant to the potential exception mentioned above. It should return null whenever the sha is not queryable.