MNT: allow repository/git revision overrides for development

meta.yaml

@@ -11,8 +11,11 @@ package:
   version: {{ version }}
 
 source:
-  git_url:   {{ repository }}
-  git_rev:   {{ version }}
+  # the FSLCONDA_REPOSITORY and FSLCONDA_REVISION
+  # environment variables can be used to override
+  # the repository/revision for development purposes.
+  git_url:   {{ os.environ.get("FSLCONDA_REPOSITORY", repository) }}
+  git_rev:   {{ os.environ.get("FSLCONDA_REVISION",   version) }}
   git_depth: 1
 
 build: