Skip pkg_resources.get_distribution call if frozen

Fixes: ticket:3259

src/allmydata/version_checks.py

@@ -23,6 +23,16 @@ from .util import (
     verlib,
 )
 
+if getattr(sys, 'frozen', None):
+    # "Frozen" python interpreters (i.e., standalone executables
+    # generated by PyInstaller and other, similar utilities) run
+    # independently of a traditional setuptools-based packaging
+    # environment, and so pkg_resources.get_distribution() cannot be
+    # used in such cases to gather a list of requirements at runtime
+    # (and because a frozen application is one that has already been
+    # "installed", an empty list suffices here).
+    _INSTALL_REQUIRES = []
+else:
     _INSTALL_REQUIRES = list(
         str(req)
         for req