Consider packages with M-A qualifiers for reverse dependencies

Strip of Multi-Arch qualifiers ":any" and ":native" when building the
dependency fields, as they are not part of the package name.

This will fix cases like

  Package: ipython3
  Depends: python3:any (>= 3)

and include ipython3 in python3's reverse dependencies.

Closes: #794194

britney.py

@@ -195,7 +195,7 @@ from britney2 import SuiteInfo, SourcePackage, BinaryPackageId, BinaryPackage
 from britney2.consts import (SOURCE, SOURCEVER, ARCHITECTURE, CONFLICTS, DEPENDS, PROVIDES, MULTIARCH)
 from britney2.excuse import Excuse
 from britney2.hints import HintParser
-from britney2.installability.builder import build_installability_tester
+from britney2.installability.builder import build_installability_tester, ma_parse_depends
 from britney2.migrationitem import MigrationItem
 from britney2.policies.policy import AgePolicy, RCBugPolicy, PiupartsPolicy, PolicyVerdict
 from britney2.utils import (old_libraries_format, undo_changes,
@@ -711,7 +711,7 @@ class Britney(object):
         return sources
 
     def _parse_provides(self, pkg_id, provides_raw):
-        parts = apt_pkg.parse_depends(provides_raw, False)
+        parts = ma_parse_depends(provides_raw)
         nprov = []
         for or_clause in parts:
             if len(or_clause) != 1:  # pragma: no cover
@@ -1004,7 +1004,7 @@ class Britney(object):
         binary_u = binaries_s_a[pkg]
 
         # local copies for better performance
-        parse_depends = apt_pkg.parse_depends
+        parse_depends = ma_parse_depends
 
         # analyze the dependency fields (if present)
         deps = binary_u.depends
@@ -1014,7 +1014,7 @@ class Britney(object):
 
 
         # for every dependency block (formed as conjunction of disjunction)
-        for block, block_txt in zip(parse_depends(deps, False), deps.split(',')):
+        for block, block_txt in zip(parse_depends(deps), deps.split(',')):
             # if the block is satisfied in testing, then skip the block
             packages = get_dependency_solvers(block, binaries_t_a, provides_t_a)
             if packages:

britney2/installability/builder.py

@@ -21,6 +21,20 @@ from britney2.utils import ifilter_except, iter_except, get_dependency_solvers
 from britney2.installability.solver import InstallabilitySolver
 
 
+def ma_parse_depends(dep_str):
+    """Parse a dependency string into a list of triples
+
+    This is like apt_pkg.parse_depends but filters out :any and :native
+    Multi-Arch prefixes. We don't use apt_pkg.parse_depends(dep_str, True)
+    as that would also filter out arch specific dependencies like :amd64.
+    """
+    res = apt_pkg.parse_depends(dep_str, False)
+    filtered = []
+    for or_clause in res:
+        filtered.append([(p.replace(':any', '').replace(':native', ''), v, r) for (p, v, r) in or_clause])
+    return filtered
+
+
 def build_installability_tester(binaries, archs):
     """Create the installability tester"""
 
@@ -43,10 +57,10 @@ def build_installability_tester(binaries, archs):
 
             # We do not differentiate between depends and pre-depends
             if pkgdata.depends:
-                depends.extend(apt_pkg.parse_depends(pkgdata.depends, False))
+                depends.extend(ma_parse_depends(pkgdata.depends))
 
             if pkgdata.conflicts:
-                conflicts = apt_pkg.parse_depends(pkgdata.conflicts, False)
+                conflicts = ma_parse_depends(pkgdata.conflicts)
 
             with builder.relation_builder(pkg_id) as relations: