[tahoe-lafs-trac-stream] [tahoe-lafs] #1258: having Tahoe or any dependency installed in site-packages (or any other shared directory) can cause us to run or test the wrong code

[tahoe-lafs]

#1258: having Tahoe or any dependency installed in site-packages (or any other
shared directory) can cause us to run or test the wrong code
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     Reporter:  davidsarah          |      Owner:  davidsarah
         Type:  defect              |     Status:  new
     Priority:  major               |  Milestone:  eventually
    Component:  dev-infrastructure  |    Version:  1.8.0
   Resolution:                      |   Keywords:  setuptools test docs
Launchpad Bug:                      |
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Comment (by davidsarah):

 Replying to [comment:26 davidsarah]:
 > I don't know how to fix this in the general case.

 To be more precise, I don't know how to do it while still using
 setuptools. If we ditched setuptools then I would know how to do it (by
 making sure that the dependencies are always added at the start of
 {{{sys.path}}}, and/or by using a custom import hook). The amount of work
 needed to replace the affected setuptools functionality shouldn't be
 underestimated, though.

 > How about if we establish a weaker goal: to detect at run-time whether
 this has happened and raise an exception if so.

 We already check that the version found by import is acceptable, except in
 the case of packages that don't declare their version in an easily
 inspectable manner (#1473). That isn't equivalent to checking whether this
 bug has occurred, though: we can (and frequently do) import a package that
 is not the version that setuptools intended to import, but that just
 happens to have an acceptable version. We know which version and path
 setuptools intended to import, and the original code I wrote to check for
 mismatches did treat this as an error. We changed it to be a warning that
 is only displayed in the situations described in comment:30, because the
 error was happening too often :-(

 (The ticket1306 branch, which did the more thorough check, has been
 deleted from the trac, so links to it no longer work. It can still be
 checked out using {{{darcs get --lazy http://tahoe-lafs.org/source/tahoe-
 lafs/ticket1306}}}, though.)

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1258#comment:28>
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