ResolveMerger throws a MissingObjectException when it encounters
a submodule conflict while merging. The reason is that it treats
the submodule link as a blob and tries to read its contents.
We solve the issue by detecting before content merge whether the
path to be merged is a submodule link, and skip the content
merge if it is.
Bug: 389238
Change-Id: I9a58dfc7716b28a21f5c04cf3a865091ae8dfe7e Signed-off-by: Tommi Siivola <tommi.siivola@eficode.com>