[SPARK-9254] [BUILD] [HOTFIX] sbt-launch-lib.bash should support HTTP/HTTPS redirection

Target file(s) can be hosted on CDN nodes. HTTP/HTTPS redirection must be supported to download these files.

Author: Cheng Lian <lian@databricks.com>

Closes #7597 from liancheng/spark-9254 and squashes the following commits:

fd266ca [Cheng Lian] Uses `--fail' to make curl return non-zero value and remove garbage output when the download fails
a7cbfb3 [Cheng Lian] Supports HTTP/HTTPS redirection

build/sbt-launch-lib.bash

@@ -51,9 +51,13 @@ acquire_sbt_jar () {
     printf "Attempting to fetch sbt\n"
     JAR_DL="${JAR}.part"
     if [ $(command -v curl) ]; then
-      (curl --silent ${URL1} > "${JAR_DL}" || curl --silent ${URL2} > "${JAR_DL}") && mv "${JAR_DL}" "${JAR}"
+      (curl --fail --location --silent ${URL1} > "${JAR_DL}" ||\
+        (rm -f "${JAR_DL}" && curl --fail --location --silent ${URL2} > "${JAR_DL}")) &&\
+        mv "${JAR_DL}" "${JAR}"
     elif [ $(command -v wget) ]; then
-      (wget --quiet ${URL1} -O "${JAR_DL}" || wget --quiet ${URL2} -O "${JAR_DL}") && mv "${JAR_DL}" "${JAR}"
+      (wget --quiet ${URL1} -O "${JAR_DL}" ||\
+        (rm -f "${JAR_DL}" && wget --quiet ${URL2} -O "${JAR_DL}")) &&\
+        mv "${JAR_DL}" "${JAR}"
     else
       printf "You do not have curl or wget installed, please install sbt manually from http://www.scala-sbt.org/\n"
       exit -1