[Buildbot] #3627: GIT supportsSubmoduleCheckout prevents to update submodule

[Buildbot trac]

#3627: GIT supportsSubmoduleCheckout prevents to update submodule
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Reporter:  nurfcake  |      Owner:
    Type:  defect    |     Status:  new
Priority:  blocker   |  Milestone:  0.9.1
 Version:  0.9.0     |   Keywords:
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 The commit
 [https://github.com/buildbot/buildbot/commit/a310e30afab77fd6b04c9f728bf73ff7d8f4d847
 a310e30afab77fd6b04c9f728bf73ff7d8f4d847] changed the default behavior for
 'submodule update'.
 From my point of view this is wrong and should not be the default value.
 Overriding the checkout policy may be a useful parameter to be added to
 the GIT constructor.

 The GIT documentation says the following for "--checkout":

 ''This is the default behavior, the main use of this option is to override
 submodule.$name.update when set to a value other than checkout. If the key
 submodule.$name.update is either not explicitly set or set to checkout,
 this option is implicit.''

 This means the only purpose for '--checkout' is to override the update
 policy to checkout mode, this is already GIT's default. There is
 technically no need to override the GIT standard.

 We have a large project with several submodules, where the .gitmodules is
 configured as follows:

 {{{
 [submodule "sub_name"]
   path = name.git
   update = none
 }}}

 Our buildbot user (and most of our userbase) do not have the access rights
 to this repository. Therefore the default policy is update = none.
 This worked correctly with 0.8.12. Overriding the update policy leads to
 checkout failure, due to missing access rights.

 In addition to that there is no possibility to oversteer this behavior, as
 this is determined by the GIT version only.

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Ticket URL: <http://trac.buildbot.net/ticket/3627>
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Buildbot: build/test automation