fix(utils): Filter out empty string releases (#2591)

Instead of only allowing truthy releases, we were allowing all non-`None` releases, which includes empty strings.

sentry_sdk/utils.py

@@ -130,7 +130,7 @@ def get_default_release():
         return release
 
     release = get_git_revision()
-    if release is not None:
+    if release:
         return release
 
     for var in (

tests/test_utils.py

@@ -5,6 +5,7 @@
 from sentry_sdk.utils import (
     Components,
     Dsn,
+    get_default_release,
     get_error_message,
     get_git_revision,
     is_valid_sample_rate,
@@ -579,3 +580,15 @@ def test_devnull_not_found():
         revision = get_git_revision()
 
     assert revision is None
+
+
+def test_default_release():
+    release = get_default_release()
+    assert release is not None
+
+
+def test_default_release_empty_string():
+    with mock.patch("sentry_sdk.utils.get_git_revision", return_value=""):
+        release = get_default_release()
+
+    assert release is None