check-branch: use expr instead of let

ctrueden · ctrueden · commit a441406c5572 · 2020-02-07T16:18:16.000-06:00
This avoids problems with dash on Ubuntu.
diff --git a/check-branch.sh b/check-branch.sh
@@ -20,9 +20,9 @@ do
   start=$(date +%s)
   mvn clean verify > "$filename" 2>&1 && result=SUCCESS || result=FAILURE
   end=$(date +%s)
-  let time="end-start"
+  time=$(expr "$end" - "$start")
   echo "$prefix $commit $result $time"
-  let count="count+1"
+  count=$(expr "$count" + 1)
 done
 
 git checkout "$branch" > /dev/null 2>&1
