Fix issue where 0'd commit sha isn't matching properly

• Fix issue where 0'd commit sha isn't matching properly

In local testing after reports by Matt + Denis, it was found the 0 matching regex wasn't behaving properly. This seems to be caused by ruby auto-casting a 0 only string to a number due to soft typing, which wasn't a problem observed before. The fix forces the var into a string before regex comparisons.

src/main/rb/eca.rb

@@ -126,7 +126,7 @@ end
 
 ## Get all new commits for branch, relative to itself for existing branch, relative to tree for new
 diff_git_commits_raw = ''
-if (previous_head_commit =~ /\0+/) then
+if (previous_head_commit.to_s =~ /^0+$/) then
   ## This isn't perfect as its relative to fork, but should be huge improvement
   diff_git_commits_raw = `git rev-list #{new_head_commit}  --not --branches=*`
 else