fix for incorrect stats computation in diff exp t-test (#2318)

* 2211 fixes

* lint

* lint

* add missing test and bug found by test

* change terminology for count distribution

* update scanpy requirement

* update scanpy requirement

backend/server/cli/launch.py

@@ -150,6 +150,14 @@ def dataset_args(func):
         metavar="<URL>",
         help="URL providing more information about the dataset (hint: must be a fully specified absolute URL).",
     )
+    @click.option(
+        "--X-approx-distribution",
+        default=DEFAULT_CONFIG.dataset_config.X_approx_distribution,
+        show_default=True,
+        type=click.Choice(["auto", "normal", "count"], case_sensitive=False),
+        help="Specify the approximate distribution of X matrix values. 'auto' will use a heuristic "
+        "to determine the approximate distribution.  Mode 'auto' is incompatible with --backed.",
+    )
     @functools.wraps(func)
     def wrapper(*args, **kwargs):
         return func(*args, **kwargs)
@@ -318,6 +326,7 @@ def launch(
     disable_diffexp,
     config_file,
     dump_default_config,
+    x_approx_distribution,
 ):
     """Launch the cellxgene data viewer.
     This web app lets you explore single-cell expression data.
@@ -376,6 +385,7 @@ def launch(
             embeddings__names=embedding,
             diffexp__enable=not disable_diffexp,
             diffexp__lfc_cutoff=diffexp_lfc_cutoff,
+            X_approx_distribution=x_approx_distribution,
         )
 
         diff = cli_config.server_config.changes_from_default()