Revert "update_depot_tools: make cipd_bin_setup failures fatal"

This reverts commit bfa05c83.

Reason for revert: breaks bot bootstrap

Original change's description:
> update_depot_tools: make cipd_bin_setup failures fatal
> 
> This should make them more noticeable.
> 
> Bug: 762568
> Change-Id: Ibd4ca4dc34d36aec5773d28454d134c909cc78dc
> Reviewed-on: https://chromium-review.googlesource.com/653157
> Reviewed-by: Daniel Jacques <dnj@chromium.org>
> Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>

TBR=phajdan.jr@chromium.org,dnj@chromium.org

Change-Id: I14e8aae77beca52ebbd21567e2ea20954e2b34d8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 762894, 762568
Reviewed-on: https://chromium-review.googlesource.com/654977Reviewed-by: Paweł Hajdan Jr. <phajdan.jr@chromium.org>
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>

update_depot_tools

@@ -121,10 +121,7 @@ if [ "X$DEPOT_TOOLS_UPDATE" != "X0" ]; then
 
   # Sync CIPD and CIPD client tools.
   source "$base_dir/cipd_bin_setup.sh"
-  cipd_bin_setup || {
-    echo "CIPD bootstrap failed"
-    exit 1
-  }
+  cipd_bin_setup
 
   find "$base_dir" -iname "*.pyc" -exec rm -f {} \;
 fi