support/testing: set $USER in rust tests

When the run-time tests to build rust and rust-bin packages are run via Docker,
the $USER environment variable is not set, which makes cargo fail when
initializing the test project.

So add it to make cargo happy.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 09a5eb427a)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/testing/tests/package/test_rust.py

@@ -21,6 +21,7 @@ class TestRustBase(infra.basetest.BRTest):
     def build_test_prog(self):
         hostdir = os.path.join(self.builddir, 'host')
         env = os.environ.copy()
+        env["USER"] = "br-user"
         env["PATH"] = "{}:".format(os.path.join(hostdir, 'bin')) + env["PATH"]
         env["CARGO_HOME"] = os.path.join(hostdir, 'usr', 'share', 'cargo')
         env["RUST_TARGET_PATH"] = os.path.join(hostdir, 'etc', 'rustc')