Remove side-effects from assert() calls. #3545

In some configurations, the compiler on Mac OS 10.8 will turn assert()
calls into no-ops, leaving the argument unevaluated. Any side-effects of
the argument (such as the ++ operator or function calls) will not occur
in this case.
Make sure we check return values.  Default to send stdout.  #3522.
Refine security design - only allow transfers of files in the sandbox. #3522
Turn off pre-release for V7_8_8-branch
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Change V7_8-branch version to 7.8.9
===VersionHistory:None===
Merge branch 'V7_8-branch' into V7_9_5-branch
Merge branch 'V7_9_5-branch'