procutil: make stream detection in make_line_buffered more correct and strict In make_line_buffered(), we don’t want to wrap the stream if we know that lines get flushed to the underlying raw stream already. Previously, the heuristic was too optimistic. It assumed that any stream which is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there are buffered streams that aren’t instances of io.BufferedIOBase, like Mercurial’s own winstdout. The new logic is different in two ways: First, only for the check, if unwraps any combination of WriteAllWrapper and winstdout. Second, it skips wrapping the stream only if it is an instance of io.RawIOBase (or already wrapped). If it is an instance of io.BufferedIOBase, it gets wrapped. In any other case, the function raises an exception. This ensures that, if an unknown stream is passed or we add another wrapper in the future, we don’t wrap the stream if it’s already line buffered or not wrap the stream if it’s not line buffered. In fact, this was already helpful during development of this change. Without it, I possibly would have forgot that WriteAllWrapper needs to be ignored for the check, leading to unnecessary wrapping if stdout is unbuffered. The alternative would have been to always wrap unknown streams. However, I don’t think that anyone would benefit from being less strict. We can expect streams from the standard library to be subclassing either io.RawIOBase or io.BufferedIOBase, so running Mercurial in the standard way should not regress by this change. Py2exe might replace sys.stdout and sys.stderr, but that currently breaks Mercurial anyway and also these streams don’t claim to be interactive, so this function is not called for them.

#!/bin/sh
#
# Use this script to generate tags.svndump
#

mkdir temp
cd temp

mkdir project-orig
cd project-orig
mkdir trunk
mkdir branches
mkdir tags
mkdir unrelated
cd ..

svnadmin create svn-repo
svnurl=file://`pwd`/svn-repo
svn import project-orig $svnurl -m "init projA"

svn co $svnurl project
cd project
echo a > trunk/a
svn add trunk/a
svn ci -m adda
echo a >> trunk/a
svn ci -m changea
echo a >> trunk/a
svn ci -m changea2
# Add an unrelated commit to test that tags are bound to the
# correct "from" revision and not a dummy one
echo a >> unrelated/dummy
svn add unrelated/dummy
svn ci -m unrelatedchange
# Tag current revision
svn up
svn copy trunk tags/trunk.v1
svn copy trunk tags/trunk.badtag
svn ci -m "tagging trunk.v1 trunk.badtag"
echo a >> trunk/a
svn ci -m changea3
# Fix the bad tag
# trunk.badtag should not show in converted tags
svn up
svn mv tags/trunk.badtag tags/trunk.goodtag
svn ci -m "fix trunk.badtag"
echo a >> trunk/a
svn ci -m changea
# Delete goodtag and recreate it, to test we pick the good one
svn rm tags/trunk.goodtag
svn ci -m removegoodtag
svn up
svn copy trunk tags/trunk.goodtag
svn ci -m recreategoodtag
cd ..

svnadmin dump svn-repo > ../tags.svndump