tests: test behavior of IOError during transactions (issue5658)...
tests: test behavior of IOError during transactions (issue5658)
ui._write(), ui._write_err(), and ui.flush() all trap IOError and
re-raise as error.StdioError. If a caller doesn't catch StdioError
when writing to stdio, it could bubble all the way to dispatch.
This commit adds tests for I/O failures around various transaction
operations.
The most notable badness is during abort. Here, an uncaught StdioError
will result in incomplete transaction rollback, requiring an
`hg rollback` to recover. This can result in a client "corrupting"
a remote repo via terminated HTTP and SSH socket.
