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+PACKING ALGORITHM
+=================
+
+Begin with a list of content set paths:
+'''
+/content/dist/rhel/$releasever/$basearch/os
+/content/dist/rhel/$releasever/$basearch/debug
+/content/dist/rhel/$releasever/$basearch/source/SRPMS
+/content/dist/jboss/source
+/content/beta/rhel/$releasever/$basearch/os
+/content/beta/rhel/$releasever/$basearch/debug
+/content/beta/rhel/$releasever/$basearch/source/SRPMS
+'''
+
+Create a prefix tree out of the paths, where each node in the tree contains the
+names of its children, rather than the children containing its own name:
+
+'''
++-------+                              +------+
+|       |                              |      |
+|-------+                              |------|
+|content+--+-------+                   |source+-+---+
++-------+  |       |                   +------+ |   |
+           |-------|                   |        |---|
+           |dist   +--------+-------+  |        +---+
+        +--+beta   |        |       |  |
+        |  +-------+        |-------|  |
+        |                   |jboss  +--+
++-------+                   |rhel   +--+
+|       |                   +-------+  |
+|-------|                              |
+|rhel   +--+-----------+               +-----------+
++-------+  |           |               |           |
+           |-----------|               |-----------|
++----------+$releasever|               |$releasever+--+
+|          +-----------+               +-----------+  |
+|                                                     |
++---------+                                 +---------+
+|         |                                 |         |
+|---------|                                 |---------|
+|$basearch+--+                           +--+$basearch|    +---+
++---------+  |                           |  +---------+    |   |
+             |                           |                 |---|
+             +--------+                  +-------+         +---+
+             |        |                  |       |         |
+             |--------|                  |-------|         |
++---+--------+os      |                  |os     +---------+
+|   |     +--+debug   |                  |debug  +-----------+---+
+|---|     |  |source  +--+               |source +--+        |   |
++---+     |  +--------+  |               +-------+  |        |---|
+          |              |                          |        +---+
+      +---+              +------+                   |
+      |   |              |      |                   +-----+
+      |---|              |------|                   |     |
+      +---+           +--+SRPMS |                   |-----|
+                      |  +------+                   |SRPMS+--+---+
+                      |                             +-----+  |   |
+                  +---+                                      |---|
+                  |   |                                      +---+
+                  |---|
+                  +---+
+'''
+
+This eliminates the duplication in the prefixes of our paths. We now only have
+one instance of the word "content", for example. We now find any duplicate
+subtrees, remove the duplicate, and point all references from the duplicate to
+the original:
+
+'''
++-------+                              +------+
+|       |                              |      |
+|-------+                              |------|
+|content+--+-------+                   |source+-+
++-------+  |       |                   +------+ | 
+           |-------|                   |        |
+           |dist   +--------+-------+  |        |
+        +--+beta   |        |       |  |        |
+        |  +-------+        |-------|  |        |
+        |                   |jboss  +--+        |
++-------+-------------------+rhel   |           |
+|       |                   +-------+           |
+|-------|                                       |
+|rhel   +--+-----------+                        |
++-------+  |           |                        |
+           |-----------|                        |
++----------+$releasever|                        |
+|          +-----------+                        |
+|                                               |
++---------+                                     |
+|         |                                     |
+|---------|                                     |
+|$basearch+--+                                  |
++---------+  |                                  |
+             |                                  |
+             +--------+                         |
+             |        |                         |
+             |--------|                         |
+     +-------+os      |                         |
+     |    +--+debug   |                         |
+     |    |  |source  +--+                      |
+     |    |  +--------+  |                      |
+     |    |              |                      |
+     |    |              +------+               |
+     |    +-------+      |      |               |
+     |            |      |------|               |
+     |            |   +--+SRPMS |               |
+     |            |   |  +------+               |
+     |            |   |                         |
+     +------------+---+-------------------------+
+                  |   |           
+                  |---|
+                  +---+
+'''
+