repo: diff: add option to show "creation event" diff for root commit

At its inception, Git did not show a "creation event" diff for a
project's root commit since early projects, such as the Linux kernel,
were already well established, and a large root diff was considered
uninteresting noise.

On the other hand, new projects adopting Git typically have small root
commits, and such a "creation event" is likely to have meaning, rather
than being pure noise. Consequently, git-diff-tree gained a --root flag
in dc26bd89 (diff-tree: add "--root" flag to show a root commit as a big
creation event, 2005-05-19), though it was disabled by default.

Displaying the root "creation event" diff, however, became the default
behavior when configuration option 'log.showroot' was added to git-log
in 0f03ca94 (config option log.showroot to show the diff of root
commits; 2006-11-23). And, gitk (belatedly) followed suit when it
learned to respect 'log.showroot' in b2b76d10 (gitk: Teach gitk to
respect log.showroot; 2011-10-04).

By default, these tools now all show the root diff as a "creation
event", however, git-arr suppresses it unconditionally. Resolve this
shortcoming by adding a new git-arr configuration option "rootdiff" to
control the behavior (enabled by default).

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>

1 files changed, 2 insertions, 2 deletions

diff --git a/git.py b/git.py
index bddca70..9a77c7c 100644
--- a/git.py
+++ b/git.py
@@ -198,8 +198,6 @@ class Repo:
     def __init__(self, path, branch = None, name = None, info = None):
         self.path = path
         self.branch = branch
-
-        # We don't need these, but provide them for the users' convenience.
         self.name = name
         self.info = info or SimpleNamespace()
 
@@ -303,6 +301,8 @@ class Repo:
         cmd.patch = None
         cmd.numstat = None
         cmd.find_renames = None
+        if (self.info.root_diff):
+            cmd.root = None
         # Note we intentionally do not use -z, as the filename is just for
         # reference, and it is safer to let git do the escaping.