Setting If-Modified-Since to last known valid-after plus 180 seconds might be problematic in test networks
From this tor-talk@ posting:
I've found some new settings from Chutney torrc template,
TestingServerDownloadSchedule and TestingClientDownloadSchedule.
Then I upgrade my tor to 0.2.5.2 since the new settings are available in
0.2.5.x and gave small values to the settings, but no help.
So I went back to source code and found that in directory.c the directory
request parameter "if_modified_since" came from "valid_after" plus a
constant 180. Though I'm not sure about the reason this number written in
numeric instead of a constant definition, I removed it and now the
consensus file in client can be updated in a period of
TestingClientDownloadSchedule!
It seems 180 seconds might indeed be a bad constant for test networks. Though I don't see what exactly breaks and why. Asked for details on tor-talk@ and made this ticket to track the issue.