rebase: extract dryrun as a function

To avoid more number of indented blocks and make it easier to add
additional functionality in dryrun, extracted as a function.

Differential Revision: https://phab.mercurial-scm.org/D3855

hgext/rebase.py

@@ -818,6 +818,23 b' def rebase(ui, repo, **opts):'
         opts[r'dest'] = '_destautoorphanrebase(SRC)'
 
     if dryrun:
+        return _dryrunrebase(ui, repo, **opts)
+    elif inmemory:
+        try:
+            # in-memory merge doesn't support conflicts, so if we hit any, abort
+            # and re-run as an on-disk merge.
+            overrides = {('rebase', 'singletransaction'): True}
+            with ui.configoverride(overrides, 'rebase'):
+                return _origrebase(ui, repo, inmemory=inmemory, **opts)
+        except error.InMemoryMergeConflictsError:
+            ui.warn(_('hit merge conflicts; re-running rebase without in-memory'
+                      ' merge\n'))
+            _origrebase(ui, repo, abort=True)
+            return _origrebase(ui, repo, inmemory=False, **opts)
+    else:
+        return _origrebase(ui, repo, **opts)
+
+def _dryrunrebase(ui, repo, **opts):
         rbsrt = rebaseruntime(repo, ui, inmemory=True,
                               opts=pycompat.byteskwargs(opts))
         with repo.wlock(), repo.lock():
@@ -834,20 +851,6 b' def rebase(ui, repo, **opts):'
                 return 0
             finally:
                 rbsrt._prepareabortorcontinue(isabort=True)
-    elif inmemory:
-        try:
-            # in-memory merge doesn't support conflicts, so if we hit any, abort
-            # and re-run as an on-disk merge.
-            overrides = {('rebase', 'singletransaction'): True}
-            with ui.configoverride(overrides, 'rebase'):
-                return _origrebase(ui, repo, inmemory=inmemory, **opts)
-        except error.InMemoryMergeConflictsError:
-            ui.warn(_('hit merge conflicts; re-running rebase without in-memory'
-                      ' merge\n'))
-            _origrebase(ui, repo, abort=True)
-            return _origrebase(ui, repo, inmemory=False, **opts)
-    else:
-        return _origrebase(ui, repo, **opts)
 
 def _origrebase(ui, repo, inmemory=False, leaveunfinished=False, rbsrt=None,
                 **opts):