Merge ~ycheng-twn/ubuntu/+source/ubiquity:0001_mark_install_enhancement into ubuntu/+source/ubiquity:ubuntu/devel

[Yuan-Chen Cheng]

This fix LP: #1891599. please check there for details.

[Julian Andres Klode (juliank)]

Both the original approach as well as the proposed one are wrong. The correct approach for marking multiple packages for installation is to

1. mark all the packages with auto_inst=False, auto_fix=False
2. mark all the packages with auto_inst=True, auto_fix=False
3. run a ProblemResolver manually

This ensures that choices are propagated correctly, if you install A, B and A depends on C|B, this would install A and B, whereas the other algorithms install A, C, and B.

review: Disapprove

Unmerged commits

6049b7e... by Yuan-Chen Cheng on 2020-08-31

fix the issue of dependency resoluton order in mark_install()

diff --git a/ubiquity/install_misc.py b/ubiquity/install_misc.py
index 7d9f771..f996272 100644
--- a/ubiquity/install_misc.py
+++ b/ubiquity/install_misc.py
@@ -934,8 +934,21 @@ class InstallBase:
                 return
 
             with cache.actiongroup():
-                for pkg in to_install:
-                    mark_install(cache, pkg)
+                while len(to_install) > 0:
+                    failed_pkgs = set()
+                    for pkg in to_install:
+                        try:
+                            mark_install(cache, pkg)
+                        except InstallStepError as err:
+                            syslog.syslog("W: error as mark_install(" +
+                                          pkg + "):" + str(err))
+                            syslog.syslog("W: will move " + pkg +
+                                          "to next iteration")
+                            failed_pkgs.append(pkg)
+                    if len(to_install) == len(failed_pkgs):
+                        raise InstallStepError(
+                            "E: Re-ordered installation still failed")
+                    to_install = failed_pkgs
 
             self.db.progress('SET', 1)
             self.progress_region(1, 10)