Ancestry for dummies

I am trying to figure out how merging treats ancestry, and in what
scenarios it would be important to use --ignore-ancestry (or not).

I spent a few hours setting up tests of varying complexity where I
branched, made some parallel changes, and then tried to merge them back
together, generally following this method.
1 Create dir R1.0/trunk
2 Copy R1.0/trunk/FeatureA/trunk
3 Make parallel changes to different parts of a file in R1.0 and
FeatureA
4 Baseline R2.0/trunk by doing svn copy of R1.0/trunk to R2.0/trunk
(ancestry retained)
5 Merge changes from FeatureA/trunk into R2.0/trunk

I noted the results, then repeated the tests with one change: Instead
of re-baselining with "svn copy", I performed an export of R1.0 and
imported it to R2.0. So they were still identical, yet all the ancestry
had been discarded in R2.0

To my surprise, the results were identical in both case. I expected
that without having an ancestry for context, the merge tool would make a
bunch of inaccurate edits. But it performed the same way in both
cases, automatically merging the simple cases, throwing conflicts for
the complex ones.

So how does ancestry relate to merging, and what is a scenario where
using or ignoring ancestry would be really important?

Thanks,
Carlton

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Received on Mon Dec 4 19:30:11 2006