Question

How do I find all all the branches that contain a particular change revision?

For instance, I commit revision 123, then I merge it to branch RC1, but not RC2.

What command(s) can I use to get that information?

Answer 1

One way would be to list all branches, and for each one listing the revision being merged in a given branch.
That information is stored in the property svn:mergeinfo:

svn mergeinfo SOURCE_URL[@REV] [TARGET[@REV]] 

Query information related to merges (or potential merges) between SOURCE-URL and TARGET.
If the --show-revs option is not provided, display revisions which have been merged from SOURCE-URL to TARGET.
Otherwise, display either merged or eligible revisions as specified by the --show-revs option.

Example:

Find out which changesets your have been merged from your trunk directory into your test branch:

$ svn propget svn:mergeinfo ^/branches/test
/branches/other:3-4
/trunk:11-13,14,16

So for a given source and target:

$ svn mergeinfo --show-revs merged ^/trunk ^/branches/test
r11
r12
r13
r14
r16
$