[oe] [meta-oe] gitpkgv: Fix $GITPKV for a single named git source

[Clemens Lang]

Hi,

here's a patch that fixes gitpkgv.bbclass in situations where SRC_URI
contains a single git repository with an explicit name set, i.e.

  SRC_URI = "git://...;name=foo"

but SRCREV_FORMAT is not set. At the moment, this causes $GITPKGV to
always be "default". If you use $GITPKGV in $PKGV, this leads to QA
errors because version numbers do not increase. This problem does not
affect recipes with multiple sources, because bitbake enforces that
SRCREV_FORMAT is set when fetching from multiple version control
systems.

While preparing this patch, I noticed a couple of other potential
problems:
 - Should gitpkgv.bbclass also support the Git Annex fetcher?
 - gitpkgv.bbclass does not work correctly with fetcher names that are
   substrings of each other. A source named foo and one named foo-tests
   with a SRVREV_FORMAT of "foo_foo-tests" does not work correctly.
   That's probably not a openembedded problem but should be addressed in
   bitbake, right?

-- 
Clemens Lang • Development Specialist
BMW Car IT GmbH • Lise-Meitner-Str. 14 • 89081 Ulm • http://bmw-carit.com
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