Merge branch 'jc/clone'

Merge branch 'jc/clone'

* jc/clone:
  Move "no merge candidate" warning into git-pull
  Use preprocessor constants for environment variable names.
  Do not create $GIT_DIR/remotes/ directory anymore.
  Introduce GIT_TEMPLATE_DIR
  Revert "fix testsuite: make sure they use templates freshly built from the source"
  fix testsuite: make sure they use templates freshly built from the source
  git-clone: lose the traditional 'no-separate-remote' layout
  git-clone: lose the artificial "first" fetch refspec
  git-pull: refuse default merge without branch.*.merge
  git-clone: use wildcard specification for tracking branches