Add --no-squash argument to git rebase-update

--no-squash makes it faster to run rebase-update when there are merge
conflicts and you know that squashing will not help. For example, I
store all of my branches in one commit each, so I know that squashing
isn't even possible because they are already squashed.

Change-Id: I2679a855ad79d602a6d1ee09c140f2fd27ae20c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2904096
Reviewed-by: Dirk Pranke <dpranke@google.com>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Joey Arhar <jarhar@chromium.org>

git_rebase_update.py

@@ -141,7 +141,7 @@ def remove_empty_branches(branch_tree):
     print(git.run('branch', '-d', branch))
 
 
-def rebase_branch(branch, parent, start_hash):
+def rebase_branch(branch, parent, start_hash, no_squash):
   logging.debug('considering %s(%s) -> %s(%s) : %s',
                 branch, git.hash_one(branch), parent, git.hash_one(parent),
                 start_hash)
@@ -162,8 +162,18 @@ def rebase_branch(branch, parent, start_hash):
   if git.hash_one(parent) != start_hash:
     # Try a plain rebase first
     print('Rebasing:', branch)
-    rebase_ret = git.rebase(parent, start_hash, branch, abort=True)
+    rebase_ret = git.rebase(parent, start_hash, branch, abort = not no_squash)
     if not rebase_ret.success:
+      if no_squash:
+        print(textwrap.dedent("""\
+        Your working copy is in mid-rebase. Either:
+         * completely resolve like a normal git-rebase; OR
+         * abort the rebase and mark this branch as dormant:
+               git config branch.%s.dormant true
+
+        And then run `git rebase-update` again to resume.
+        """ % branch))
+        return False
       # TODO(iannucci): Find collapsible branches in a smarter way?
       print("Failed! Attempting to squash", branch, "...", end=' ')
       sys.stdout.flush()
@@ -235,6 +245,9 @@ def main(args=None):
                            'if none specified.')
   parser.add_argument('--keep-empty', '-e', action='store_true',
                       help='Do not automatically delete empty branches.')
+  parser.add_argument(
+      '--no-squash', action='store_true',
+      help='Will not try to squash branches when rebasing fails.')
   opts = parser.parse_args(args)
 
   if opts.verbose:  # pragma: no cover
@@ -295,7 +308,7 @@ def main(args=None):
     if git.is_dormant(branch):
       print('Skipping dormant branch', branch)
     else:
-      ret = rebase_branch(branch, parent, merge_base[branch])
+      ret = rebase_branch(branch, parent, merge_base[branch], opts.no_squash)
       if not ret:
         retcode = 1
 

man/html/git-rebase-update.html

@@ -756,7 +756,7 @@ git-rebase-update(1) Manual Page
 <h2 id="_synopsis">SYNOPSIS</h2>
 <div class="sectionbody">
 <div class="verseblock">
-<pre class="content"><em>git rebase-update</em> [-v | --verbose] [-n | --no-fetch] [-k | --keep-going]</pre>
+<pre class="content"><em>git rebase-update</em> [-v | --verbose] [-n | --no-fetch] [-k | --keep-going] [--no-squash]</pre>
 <div class="attribution">
 </div></div>
 </div>
@@ -869,6 +869,14 @@ Restoration
 </p>
 </dd>
 <dt class="hdlist1">
+--no-squash
+</dt>
+<dd>
+<p>
+  Skip the squash phase of rebase-update when there are merge conflicts.
+</p>
+</dd>
+<dt class="hdlist1">
 -v
 </dt>
 <dt class="hdlist1">

man/src/git-rebase-update.txt

@@ -9,7 +9,7 @@ include::_git-rebase-update_desc.helper.txt[]
 SYNOPSIS
 --------
 [verse]
-'git rebase-update' [-v | --verbose] [-n | --no-fetch] [-k | --keep-going]
+'git rebase-update' [-v | --verbose] [-n | --no-fetch] [-k | --keep-going] [--no-squash]
 
 DESCRIPTION
 -----------
@@ -78,6 +78,9 @@ OPTIONS
 --no-fetch::
   Skip the `git fetch` phase of rebase-update.
 
+--no-squash::
+  Skip the squash phase of rebase-update when there are merge conflicts.
+
 -v::
 --verbose::
   More text than your terminal can handle.