How do I find out which changelists (not files) need integrating from one branch to another?
You can compare the outputs of the p4 changes -i command. For example:p4 changes -i //depot/target/... > output1 p4 changes -i //depot/source/... > output2 diff output1 output2Changelists in output2 that aren't also in output1 are candidates for integration. However, be aware that if any file revision associated with changelist n was integrated from //depot/target/... into //depot/source/..., then changelist n will show up in both output1 and output2. So this method can be used as a rough indicator, but it's not as reliable as:p4 integ -n //depot/source/... //depot/target/...which shows you which files in the target branch need revisions integrated from the source branch.