slapos-testing: checkout slapos.recipe.cmmi using system git for bootstrap issues

software/slapos-testing/software.cfg

@@ -141,6 +141,10 @@ repository = https://lab.nexedi.com/nexedi/slapos.recipe.build.git
 [slapos.recipe.cmmi-repository]
 <= git-clone-repository
 repository = https://lab.nexedi.com/nexedi/slapos.recipe.cmmi.git
+# We use the system git and not slapos provided one, because slapos git needs
+# slapos.recipe.cmmi to be installed. This circular dependency cause parts to
+# be reinstalled everytime buildout is run because signatures are not stable.
+git-executable = git
 
 [slapos.toolbox-repository]
 <= git-clone-repository