Unreliability of the build system

[Jan Stolarek]

> This has never happened to me.  I can't even guess why it might happen to
> you.
Looking through the validation log I see that tests fail with this error message:

Actual stderr output differs from expected:
--- /dev/null	2013-05-14 15:38:10.771000000 +0200
+++ ../../libraries/base/tests/IO/T3307.run.stderr	2013-05-15 09:21:45.695049002 +0200
@@ -0,0 +1,2 @@
+WARNING: cache is out of date: /dane/uczelnia/projekty/ghc-validate/bindisttest/install   
dir/lib/ghc-7.7.20130514/package.conf.d/package.cache
+  use 'ghc-pkg recache' to fix.
*** unexpected failure for T3307(normal)

Any ideas why this happens?

Janek