OTWO-5773 Check for head_token before git fetch

Before ohloh_scm v3, we used to check for head_token before doing a git
fetch. In v3, we instead did a simple check for git operation. Since we
have a new *index.lock* issue in ohloh_scm v3, we can try reverting back
to older logic to help narrow down the cause.

Author: notalex

lib/ohloh_scm/git/scm.rb

@@ -27,7 +27,7 @@ def vcs_path
 
       def clone_or_fetch(remote_scm, callback)
         callback.update(0, 1)
-        if status.branch?(branch_name)
+        if status.exist? && status.branch?(branch_name)
           clean_and_checkout_branch # must be on correct branch, but we want to be careful.
           fetch_new_commits(remote_scm)
         else
@@ -43,7 +43,7 @@ def fetch_new_commits(remote_scm)
       end
 
       def clone_and_create_tracking_branch(remote_scm)
-        unless status.scm_dir_exist?
+        unless status.exist?
           run "rm -rf '#{url}'"
           run "git clone -q -n '#{remote_scm.url}' '#{url}'"
         end

lib/ohloh_scm/version.rb

@@ -2,7 +2,7 @@
 
 module OhlohScm
   module Version
-    STRING = '3.0.6'
+    STRING = '3.0.7'
     GIT = '2.17.1'
     SVN = '1.9.7'
     CVSNT = '2.5.04'