plugins/sources/git.py: Do not checkout submodules by default

We do not want download things from internet when building the
user have not specify in their .bst files

NEWS

@@ -2,6 +2,8 @@
 buildstream 1.3.1
 =================
 
+  o BREAKING CHANGE: The git plugin does not checkout submodules by default anymore
+
   o BREAKING CHANGE: The 'manual' element lost its default 'MAKEFLAGS' and 'V'
     environment variables. There is already a 'make' element with the same
     variables. Note that this is a breaking change, it will require users to

buildstream/plugins/sources/git.py

@@ -52,8 +52,8 @@ git - stage files from a git repository
    ref: d63cbb6fdc0bbdadc4a1b92284826a6d63a7ebcd
 
    # Optionally specify whether submodules should be checked-out.
-   # If not set, this will default to 'True'
-   checkout-submodules: True
+   # If not set, this will default to 'False'
+   checkout-submodules: False
 
    # If your repository has submodules, explicitly specifying the
    # url from which they are to be fetched allows you to easily
@@ -379,7 +379,7 @@ class GitSource(Source):
             raise SourceError("{}: Git sources require a ref and/or track".format(self),
                               reason="missing-track-and-ref")
 
-        self.checkout_submodules = self.node_get_member(node, bool, 'checkout-submodules', True)
+        self.checkout_submodules = self.node_get_member(node, bool, 'checkout-submodules', False)
         self.submodules = []
 
         # Parse a dict of submodule overrides, stored in the submodule_overrides

tests/cachekey/project/sources/git1.expected

-4e03d21335e578034b09191ebf4977f0f537425c3031805dfb2f835ff77925cd
\ No newline at end of file
+18de2eff9b2caa49a959b6c0e023cbd522f96d84d1b85634fe2064f5080f4856

tests/cachekey/project/sources/git2.expected

-75c96f6c8d3ca3ffe164cd51f42689287021e60ef524f56340539feadd5a9fb8
\ No newline at end of file
+62685c106f9ff1be82d4bba3e222d39de2e45303c6abe753ae32c240e35183fc

tests/cachekey/project/sources/pip1.expected

-d8bdc8848e4d2e3d70a1267e73bf0e63afa778e4c905cad1a94308634176fb87
\ No newline at end of file
+5bc44ad07800ba40ea2baa06e2c3d8c8e34b606ca1a47f69e70340adc5b0acaa

tests/cachekey/project/target.expected

-125d9e7dcf4f49e5f80d85b7f144b43ed43186064afc2e596e57f26cce679cf5
\ No newline at end of file
+118c3729aa12dec3730f3ab50af4c00297595f6d2fdd2730f384f61ce4cf069f

tests/sources/git/project-override/project.conf

@@ -3,7 +3,7 @@ name: foo
 sources:
   git:
     config:
-      checkout-submodules: False
+      checkout-submodules: True
 elements:
   manual:
     config: