ci, build/f_repos: Minor UX improvements

After Armband rework landed of top of `build/f_repos` mechanism [1],
the following minor UX improvements can also be applied to Fuel's
f_repos:
- set SHELL to "/bin/sh" (we don't use any bash-isms);
- improve "From SHA..." removal for exported patches;
- force checkout of root tag commit during clean;
- silence progress during git clone (cleaner logs);
- support git older than 1.8.4 in `make clean` (fix Armband deploy);

FIXME:
 Pass TERM as Docker env var until [2] is fixed in Docker 1.13.

v4 -> v5:
 * Moved `export TERM` to Releng, where it actually belongs [3];
 * Fixed Armband deploys fail [4] by adjusting `make clean`;

[1] https://gerrit.opnfv.org/gerrit/#/c/22791/
[2] https://github.com/docker/docker/issues/9299
[3] https://gerrit.opnfv.org/gerrit/#/c/22933/
[4] https://build.opnfv.org/ci/view/armband/job/\
    fuel-deploy-armband-baremetal-daily-master/57/consoleText

Fixes: FUEL-200

Change-Id: I80e3074f8659769e21f5b56f07c34c7a5de727bc
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/build/config.mk b/build/config.mk
index ab30518b5..e5ca615e0 100644
--- a/build/config.mk
+++ b/build/config.mk
@@ -8,7 +8,11 @@
 # http://www.apache.org/licenses/LICENSE-2.0
 ##############################################################################
 
-# fuel-main tag checked out from upstream `fuel-main` repo before patching it
+# This tag is NOT checked out, it only serves a cosmetic purpose of hinting
+# what upstream Fuel components our submodules are bound to (while tracking
+# remotes, ALL submodules will point to remote branch HEAD).
+# NOTE: Pinning fuel-main or other submodules to a specific commit/tag is
+# done ONLY via git submodules.
 FUEL_MAIN_TAG = 9.0.1
 MOS_VERSION   = 9.0
 OPENSTACK_VERSION = mitaka-9.0