release-sr: Fix usage for various cases

Fixes:
  * fail fast in case of trouble
  * treat 1.0 as special working branch and be ok to remove it
  * select origin/1.0 as source of the local 1.0 branch

Thank to this it can be used in clean repository.

release-sr

 #!/bin/bash
 
-git fetch
+set -e
+
+git fetch --all
+
+# Go to master
+git checkout master
+
+# Clean up 1.0
+git branch -D 1.0 || echo
+
+# Checkout 1.0
+git checkout origin/1.0 -b 1.0
 
-git checkout 1.0
 git reset origin/1.0 --hard
 
 # for now this script is hardcoded to release on 1.0.x versions intentionally