Add a regression test for SOURCE_DATE_EPOCH

Since bazel 0.10.0 and 0.11.0 were shipped with SOURCE_DATE_EPOCH interpreted
as Kiloseconds rather than seconds since the epoch as it should, extend our test
to also verify that the correct year is shown.

Change-Id: I613d1a967e4e36019b55b720a4b9b7757cfb4b60
PiperOrigin-RevId: 187009490

src/test/shell/bazel/bazel_bootstrap_distfile_test.sh

@@ -43,7 +43,7 @@ function test_bootstrap()  {
     mkdir -p "${WRKDIR}" || fail "Could not create workdir"
     trap "rm -rf \"$WRKDIR\"" EXIT
     cd "${WRKDIR}" || fail "Could not change to work directory"
-    export SOURCE_DATE_EPOCH=1501234567
+    export SOURCE_DATE_EPOCH=1501234567 # Fri Jul 28 09:36:07 UTC 2017
     _log_progress "unzip"
     unzip -q "${DISTFILE}"
     _log_progress "bootstrap"
@@ -54,6 +54,9 @@ function test_bootstrap()  {
     ./output/bazel shutdown
     _log_progress "assert"
     expect_log "${SOURCE_DATE_EPOCH}"
+    expect_log 2017      # The year 1501234567 seconds since the epoch
+    expect_not_log 49542 # The year 1501234567000 seconds since the epoch
+    expect_not_log 1970  # The year 1501234 seconds since the epoch
     cd "${olddir}"
     _log_progress "done"
 }