Don't use variables that conflict with the nixos test-driver's namespace.

nixos/tests/private-storage.nix

@@ -209,8 +209,8 @@ in {
     try:
       ${runOnNode "introducer" [ run-introducer "/tmp/node.pem" (toString introducerPort) introducerFURL ]}
     except:
-      code, log = introducer.execute('cat /tmp/stdout /tmp/stderr')
-      introducer.log(log)
+      code, output = introducer.execute('cat /tmp/stdout /tmp/stderr')
+      introducer.log(output)
       raise
 
     #
@@ -244,8 +244,8 @@ in {
     try:
       api_stripe_com.wait_for_unit("api.stripe.com")
     except:
-      code, log = api_stripe_com.execute('journalctl -u api.stripe.com')
-      api_stripe_com.log(log)
+      code, output = api_stripe_com.execute('journalctl -u api.stripe.com')
+      api_stripe_com.log(output)
       raise
 
     # Get some ZKAPs from the issuer.
@@ -259,20 +259,20 @@ in {
       ]}
     except:
       code, log = client.execute('cat /tmp/stdout /tmp/stderr');
-      client.log(log)
+      client.log(output)
 
       # Dump the fake Stripe API server logs, too, since the error may arise
       # from a PaymentServer/Stripe interaction.
-      code, log = api_stripe_com.execute('journalctl -u api.stripe.com')
-      api_stripe_com.log(log)
+      code, output = api_stripe_com.execute('journalctl -u api.stripe.com')
+      api_stripe_com.log(output)
       raise
 
     # The client should be prepped now.  Make it try to use some storage.
     try:
       ${runOnNode "client" [ exercise-storage "/tmp/client" ]}
     except:
-      code, log = client.execute('cat /tmp/stdout /tmp/stderr')
-      client.log(log)
+      code, output = client.execute('cat /tmp/stdout /tmp/stderr')
+      client.log(output)
       raise
 
     # It should be possible to restart the storage service without the
@@ -285,16 +285,16 @@ in {
       if (before != after):
         raise Exception('fURL changes after storage node restart')
     except:
-      code, log = storage.execute('cat /tmp/stdout /tmp/stderr')
-      storage.log(log)
+      code, output = storage.execute('cat /tmp/stdout /tmp/stderr')
+      storage.log(output)
       raise
 
     # The client should actually still work, too.
     try:
       ${runOnNode "client" [ exercise-storage "/tmp/client" ]}
     except:
-      code, log = client.execute('cat /tmp/stdout /tmp/stderr')
-      client.log(log)
+      code, output = client.execute('cat /tmp/stdout /tmp/stderr')
+      client.log(output)
       raise
 
     # The issuer metrics should be accessible from the monitoring network.