Bug 1358257

https://github.com/ManageIQ/manageiq/pull/9747

Update: after discussion on PR #9747, we switched to behavior 2 
(create `Foo : <emtpy value>` tags).

New commit detected on ManageIQ/manageiq/master:
https://github.com/ManageIQ/manageiq/commit/90155b96186a036c5e406ee5308921521c524535

commit 90155b96186a036c5e406ee5308921521c524535
Author:     Beni Cherniavsky-Paskin <cben>
AuthorDate: Mon Jul 25 20:00:51 2016 +0300
Commit:     Beni Cherniavsky-Paskin <cben>
CommitDate: Mon Jul 25 20:02:05 2016 +0300

    Fix auto-tagging to handle empty-value labels
    
    Given any-value mapping `foo` -> "Foo" category,
    `foo=` label will create "Foo : <empty value>" tag.
    
    Fixes #9713,
    https://bugzilla.redhat.com/show_bug.cgi?id=1358257
    https://bugzilla.redhat.com/show_bug.cgi?id=1358303

 app/models/container_label_tag_mapping.rb       | 11 +++++++++--
 spec/models/container_label_tag_mapping_spec.rb |  7 ++++---
 2 files changed, 13 insertions(+), 5 deletions(-)

Forgot to mention in description:
after using `rails console` to create the mapping in the DB, 
should restart CFME to reload it.
(it's cached in memory indefinitely; the `ContainerLabelTagMapping.drop_cache` line above affects the rails console process but not an already running instance).

New commit detected on ManageIQ/manageiq/master:
https://github.com/ManageIQ/manageiq/commit/593a0cd8930e3ceb093da1fe4d44301a0e448f9d

commit 593a0cd8930e3ceb093da1fe4d44301a0e448f9d
Author:     Beni Cherniavsky-Paskin <cben>
AuthorDate: Thu Oct 13 21:43:40 2016 +0300
Commit:     Beni Cherniavsky-Paskin <cben>
CommitDate: Wed Oct 26 20:04:51 2016 +0300

    Do not create tags for empty-value labels
    
    This reverts decision on
    https://github.com/ManageIQ/manageiq/issues/9713#issuecomment-233929144
    https://bugzilla.redhat.com/show_bug.cgi?id=1358257
    back to "behavior 1" of ignoring labels with empty value.
    
    This only affects any-value mappings.
    A specific value='' mapping would still be honored.

 app/models/container_label_tag_mapping.rb       | 14 ++++++--------
 spec/models/container_label_tag_mapping_spec.rb |  6 ++----
 2 files changed, 8 insertions(+), 12 deletions(-)

`oc label`, `oc edit` apparently gives error on empty label value in newer openshift (v3.3).  Found a different way using curl.
And there is now UI to configure mappings (https://github.com/ManageIQ/manageiq/pull/11591).
And expected behavior changed to no tag.

==> UPDATED INSTRUCTIONS:

(Steps 2 & 3 below could be skipped but then it's hard to know step 5 worked.)

 1. Top right menu -> Configuration -> Region 0 in explorer -> Map Tags tab.
    Add a mapping rule from Entity type <ALL>, Label "foo" to category "Foo Whatever".

 2. Create `foo=bar` label on some entity, let's say a pod:

    $ oc label pod --namespace=default router-1-l67gi foo=bar

 3. Refresh the provider.
    Expected results:
    - Provider screen shows Last Refresh Status "successful" with recent time (e.g. 1 minute ago).
    - The entity's screen shows "foo | bar"  label in Labels table AND "Foo Whatever : bar" tag in "Smart Management" table.

 4. Change the label to empty value:

    $ oc proxy --port=9443 &
    [1]
    Starting to serve on 127.0.0.1:9443
    $ curl -XPATCH  -H "Content-Type: application/strategic-merge-patch+son" http://localhost:8080/api/v1/namespaces/default/pods/router-1-l67gi -d '{"metadata":{"labels":{"foo":""}}}' | grep --after=5 labels
    $ fg
    oc proxy --port=9443
    ^C

 5. Refresh the provider.

    Expected results:
    - Provider screen shows Last Refresh Status "successful" with recent time (e.g. 0 minute ago).
    - The entity's screen shows "foo |"  empty label in Labels table AND NO TAG in "Smart Management" table.

[If you want to label other entity types, the URL structure differs, search "PATCH" in http://kubernetes.io/docs/api-reference/v1/operations/.  To label a Project, use `oc label namespace NAME` and /api/v1/namespaces/NAME.]

Corrections to step 4:
- the oc proxy port should match port used in curl
- s/+son/+json/

 4. Change the label to empty value:

    $ oc proxy --port=8080 &
    [1]
    Starting to serve on 127.0.0.1:9443
    $ curl -XPATCH  -H "Content-Type: application/strategic-merge-patch+json" http://localhost:8080/api/v1/namespaces/default/pods/router-1-l67gi -d '{"metadata":{"labels":{"foo":""}}}' | grep --after=5 labels
    $ fg
    oc proxy --port=8080
    ^C


P.S. To label projects, use url of the form http://localhost:8080/api/v1/namespaces/NAME

Verified. 
Followed steps in comment 7 and comment 8 
As below: 
$ oc proxy --port=9443 &

$curl -XPATCH  -H "Content-Type: application/strategic-merge-patch+json" http://localhost:9443/api/v1/namespaces/hello4 -d '{"metadata":{"labels":{"dept":""}}}' | grep --after=5 labels
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed

Viewing Project in CFME, for Project=hello4, Labels table has empty values for dept.