py3: don't assert on byte types in python 2

Summary:
We don't have confidence that python 2 is only using bytes (vs unicode
or other byte-like objects). These asserts break users, so let's disable them
except for in tests. We should uncover issues here as we port to python 3.

Reviewed By: xavierd

Differential Revision: D19819699

fbshipit-source-id: 9e3a9c34e7661fac4db9ee2a79f65be3d5e48cb3

eden/scm/edenscm/mercurial/pycompat.py

@@ -54,6 +54,19 @@ def identity(a):
     return a
 
 
+# Copied from util.py to avoid pycompat depending on Mercurial modules
+if "TESTTMP" in os.environ or "testutil" in sys.modules:
+
+    def istest():
+        return True
+
+
+else:
+
+    def istest():
+        return False
+
+
 if sys.version_info[0] >= 3:
     import builtins
     import functools
@@ -165,12 +178,15 @@ else:
 
     def encodeutf8(s):
         # type: (bytes) -> bytes
-        assert isinstance(s, bytes)
+        if istest():
+            assert isinstance(s, bytes)
+
         return s
 
     def decodeutf8(s, errors="strict"):
         # type: (bytes, str) -> bytes
-        assert isinstance(s, bytes)
+        if istest():
+            assert isinstance(s, bytes)
         return s
 
     def iteritems(s):