Merge ~racb/git-ubuntu:style-on-imports into git-ubuntu:master

[Robie Basak]

Make Jenkins happy

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:0693d94738465199de341a3eb71922ba61cd167d
https://jenkins.ubuntu.com/server/job/git-ubuntu-ci/426/
Executed test runs:
    SUCCESS: VM Setup
    SUCCESS: Build
    SUCCESS: Unit Tests
    IN_PROGRESS: Declarative: Post Actions

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review: Approve (continuous-integration)

[Bryce Harrington (bryce)]

Totally agreed, IIRC this is the style Launchpad uses in its codebase, and it's what I do in my own projects.

I tend not to care how each section is sorted, but doing so alphabetically works fine for me.

review: Approve

diff --git a/doc/STYLE.md b/doc/STYLE.md
index 497edf0..d7ee95b 100644
--- a/doc/STYLE.md
+++ b/doc/STYLE.md
@@ -30,3 +30,17 @@
 
  * In snapcraft.yaml, cache external dependencies on our infrastructure
    wherever possible.
+
+ * Divide imports into three sections separated by a blank line:
+
+   1) Standard library imports (eg. collections, time, unittest.mock).
+   2) Third party library imports (eg. pytest).
+   3) Project-specific imports (eg. `import gitubuntu.git_repository as
+      git_repository`).
+
+   This avoids hiding a small number of project-specific or third party
+   library imports into a wall of standard library imports, giving the
+   reader an immediately clearer view of the less usual entries being
+   brought into the namespace.
+
+ * Keep imports sorted. This keeps diffs cleaner.