mercurial - Why is a --new-branch flag needed?

Question

Isn't this a normal workflow?

[default] $ hg branch foo

[foo] $ [... some commits ...]

[foo] $ hg update default

[default] $ hg merge foo

[default] $ hg commit -m "merged foo"

[default] $ hg push
abort: push creates new remote branches: foo!
(use 'hg push --new-branch' to create new remote branches)

What is the otherwise ideal way to do branching → merging → pushing?

Answer 1

The mercurial philosophy is that you should not be pushing things which make it harder for other users of the repository. Relevant to this question is that multiple heads make it harder for other developers, since they would then need to merge your changes. Hence by default pushing new heads is rejected by the server. The -f option was used to allow pushing new heads.

However, the case of pushing a new named branch is quite different conceptually to pushing a new head on the same branch. Many workflows (including mine) do each task on a separate named branch. The --new-branch option allows you to push up a new branch, whilst rejecting new heads on existing branches. It's also different (as you've seen) because it's needed even if the new branch does not create a new head (due to merging).

My personal feeling is that new branches should be allowed by default, but the mercurial developers prefer otherwise.