add-ons: Fix conda commands

As some commands are case sensitive and other not, always normalize
package names to lowercase. When uninstalling, run pip uninstall only
when that package could not be uninstalled with conda.

Orange/canvas/application/addons.py

@@ -776,20 +776,24 @@ def _next(self):
                 self.setStatusMessage(
                     "Installing {}".format(pkg.installable.name))
                 if self.conda:
-                    self.conda.install(pkg.installable)
+                    self.conda.install(pkg.installable, raise_on_fail=False)
                 self.pip.install(pkg.installable)
             elif command == Upgrade:
                 self.setStatusMessage(
                     "Upgrading {}".format(pkg.installable.name))
                 if self.conda:
-                    self.conda.upgrade(pkg.installable)
+                    self.conda.upgrade(pkg.installable, raise_on_fail=False)
                 self.pip.upgrade(pkg.installable)
             elif command == Uninstall:
                 self.setStatusMessage(
                     "Uninstalling {}".format(pkg.local.project_name))
                 if self.conda:
-                    self.conda.uninstall(pkg.local)
-                self.pip.uninstall(pkg.local)
+                    try:
+                        self.conda.uninstall(pkg.local, raise_on_fail=True)
+                    except CommandFailed:
+                        self.pip.uninstall(pkg.local)
+                else:
+                    self.pip.uninstall(pkg.local)
         except CommandFailed as ex:
             self.error.emit(
                 "Command failed: python {}".format(ex.cmd),
@@ -885,17 +889,26 @@ def _find_conda(self):
             os.environ["CONDA_DEFAULT_ENV"] = bin
             return conda
 
-    def install(self, pkg):
-        cmd = ["conda", "install", "--yes", "--quiet", pkg.name]
-        run_command(cmd, raise_on_fail=False)
-
-    def upgrade(self, pkg):
-        cmd = ["conda", "upgrade", "--yes", "--quiet", pkg.name]
-        run_command(cmd, raise_on_fail=False)
-
-    def uninstall(self, dist):
-        cmd = ["conda", "uninstall", "--yes", dist.project_name]
-        run_command(cmd, raise_on_fail=False)
+    def install(self, pkg, raise_on_fail=False):
+        cmd = ["conda", "install", "--yes", "--quiet",
+               self._normalize(pkg.name)]
+        run_command(cmd, raise_on_fail=raise_on_fail)
+
+    def upgrade(self, pkg, raise_on_fail=False):
+        cmd = ["conda", "upgrade", "--yes", "--quiet",
+               self._normalize(pkg.name)]
+        run_command(cmd, raise_on_fail=raise_on_fail)
+
+    def uninstall(self, dist, raise_on_fail=False):
+        cmd = ["conda", "uninstall", "--yes",
+               self._normalize(dist.project_name)]
+        run_command(cmd, raise_on_fail=raise_on_fail)
+
+    def _normalize(self, name):
+        # Conda 4.3.30 is inconsistent, upgrade command is case sensitive
+        # while install and uninstall are not. We assume that all conda
+        # package names are lowercase which fixes the problems (for now)
+        return name.lowercase()
 
     def __bool__(self):
         return bool(self.conda)