depsolve: penalize conflicting providers (v2). BZ 1713649

This is a corrected version of my original patch (commit ae2d51b).

For technical details and motivations, please see that other commit's
message.

yum/depsolve.py

@@ -1504,6 +1504,14 @@ def _info_req(x, y):
  return True
  return False
 
+ def _conflict_req(x, y):
+ if y is None:
+ return False
+ for ydep in y.conflicts:
+ if x.checkPrco('provides', ydep):
+ return True
+ return False
+
  def _compare_arch_distance(x, y, req_compare_arch):
  # take X and Y package objects
  # determine which has a closer archdistance to compare_arch
@@ -1558,6 +1566,7 @@ def _pkg2prov_version(pkg, provname):
  pkgs = unique_nevra_pkgs.values()
 
  pkgresults = {}
+ penalize = set()
 
  for pkg in pkgs:
  pkgresults[pkg] = 0
@@ -1671,6 +1680,10 @@ def _pkg2prov_version(pkg, provname):
  self.verbose_logger.log(logginglevels.DEBUG_4,
  _('informational req %s and %s' % (po, reqpo)))
  pkgresults[po] += 333
+ if _conflict_req(po, reqpo):
+ self.verbose_logger.log(logginglevels.DEBUG_4,
+ _('conflict req %s and %s' % (po, reqpo)))
+ penalize.add(po)
  if self.isPackageInstalled(po.base_package_name):
  self.verbose_logger.log(logginglevels.DEBUG_4,
  _('base package %s is installed for %s' % (po.base_package_name, po)))
@@ -1755,6 +1768,13 @@ def _pkg2prov_version(pkg, provname):
  pkgresults[po] += 1000
  pkgresults[po] += (len(po.name)*-1)
 
+ # Bump down any packages that we identified as "last-resort" in such a
+ # way that they all score below the worst overall score whilst keeping
+ # their relative differences.
+ shift = max(pkgresults.values()) - min(pkgresults.values()) + 1
+ for po in penalize:
+ pkgresults[po] -= shift
+
  bestorder = sorted(pkgresults.items(),
  key=lambda x: (x[1], x[0]), reverse=True)
  self.verbose_logger.log(logginglevels.DEBUG_4,