git.py: Allow setting of submodule push branch

[rleigh-codelibre]

--push is used to set the branch in .gitmodules.

[rleigh-codelibre]

Green in https://ci.openmicroscopy.org/view/Mgmt/job/SCC-merge/957/console

[sbesson]

The synchronization of submodule.<name>.branch with the --push-branch API makes sense in the context of the new feature introduced in #225.
One question about the default contract when modifying .gitmodules. As for the previous improvements to support tracking branches, we could also capture the expected behavior via integration tests.

[sbesson]

In the case where --push-branch is not passed to the original command, am I correct that with the current implementation scc merge <xxx> --update-gitmodules would unconditionally write branch = origin in the .gitmodules?

My expectation would be that in that case, we might not want to modify this key i.e. set the default here to None and conditionally skip the setting of submodule.<name>.branch.

[rleigh-codelibre]

Please see the additional commit.

[rleigh-codelibre]

Green in https://ci.openmicroscopy.org/view/Mgmt/job/SCC-merge/958/console

[sbesson]

Functionally tested using the sandbox repository. Without --push arguments

(venv) sbesson@ls30630:snoopys-sandbox ((aed9f2f...)) $ python /opt/ome/snoopycrimecop/scc/main.py merge dev_4_4  --update-gitmodules 
2018-02-14 13:56:42,538 [   scc.merge] INFO  Merging Pull Request(s) based on dev_4_4
...
2018-02-14 13:56:55,976 [   scc.merge] INFO  
(venv) sbesson@ls30630:snoopys-sandbox ((3ea130c...)) $ git diff HEAD^
diff --git a/snoopys-sandbox-2 b/snoopys-sandbox-2
index 33abb18..1b59ef2 160000
--- a/snoopys-sandbox-2
+++ b/snoopys-sandbox-2
@@ -1 +1 @@
-Subproject commit 33abb18f09519d2174a86e1933a6d62dc959f2f9
+Subproject commit 1b59ef2408a95c22030614b3be75a50e658f6cd0

With --push arguments

(venv) sbesson@ls30630:snoopys-sandbox ((aed9f2f...)) $ python /opt/ome/snoopycrimecop/scc/main.py merge dev_4_4  --update-gitmodules --push test
2018-02-14 13:57:35,872 [   scc.merge] INFO  Merging Pull Request(s) based on dev_4_4
...
2018-02-14 13:57:56,995 [   scc.merge] INFO  Merged branch pushed to https://github.com/sbesson/snoopys-sandbox/tree/test
(venv) sbesson@ls30630:snoopys-sandbox ((2ca119a...)) $ git diff HEAD^
diff --git a/.gitmodules b/.gitmodules
index b0dae12..9a6e374 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,4 @@
 [submodule "snoopys-sandbox-2"]
        path = snoopys-sandbox-2
        url = git://github.com/openmicroscopy/snoopys-sandbox-2
+       branch = test
diff --git a/snoopys-sandbox-2 b/snoopys-sandbox-2
index 33abb18..53b6588 160000
--- a/snoopys-sandbox-2
+++ b/snoopys-sandbox-2
@@ -1 +1 @@
-Subproject commit 33abb18f09519d2174a86e1933a6d62dc959f2f9
+Subproject commit 53b65889596635873a10ef0060a4739cce6860af

Using my local scc version (0.8.0), both commands result in the first behavior. This seems to match the expectation from the description of this PR.

As a side note, I realized that the submodule URL are not updated for this sandbox repository. This is likely related to pattern of the URL which does not match the expectation from the library (not ending in .git). THis is independent of this PR but probably worth fixing if we start writing integration tests assessing the content of .gitmodules.

[joshmoore]

Reading that as good to go for 0.9.2. Merging & releasing.