setup.py: Don't fail if pip fails in cmake err msg

When cmake is not found, the error message suggests what to do to
install cmake. But if `distro` is not found and cannot be installed,
the distro specific error message cannot be shown. Hence, we simply
ignore this and continue on.

Also, make the pip install quiet so that if there is an error message
in that, the user does not get confused by it.

setup.py

@@ -468,26 +468,30 @@ class build(_build):
                         message = msg_pkgmanager.format('OSX', manager)
                         break
             elif sys.platform.startswith('linux'):
-                distname = None
                 try:
                     import distro
-                except ImportError:
+                except ImportError as err:
                     import pip
-                    pip_exit = pip.main(['install', 'distro'])
+                    pip_exit = pip.main(['install', '-q', 'distro'])
                     if pip_exit > 0:
-                        raise SystemExit('Pip was unable to install `distro`')
-                    import distro
-                distname = distro.id()
-                if distname in ('debian', 'ubuntu'):
-                    message = msg_pkgmanager.format(
-                        distname.title(), 'apt-get')
-                elif distname in ('fedora', 'centos', 'redhat'):
-                    pkgmanagers = ("dnf", "yum")
-                    for manager in pkgmanagers:
-                        if find_executable(manager) is not None:
-                            message = msg_pkgmanager.format(
-                                distname.title(), manager)
-                            break
+                        log.debug("Unable to install `distro` to identify "
+                                  "the recommended command. Falling back "
+                                  "to default error message.")
+                        distro = err
+                    else:
+                        import distro
+                if not isinstance(distro, ImportError):
+                    distname = distro.id()
+                    if distname in ('debian', 'ubuntu'):
+                        message = msg_pkgmanager.format(
+                            distname.title(), 'apt-get')
+                    elif distname in ('fedora', 'centos', 'redhat'):
+                        pkgmanagers = ("dnf", "yum")
+                        for manager in pkgmanagers:
+                            if find_executable(manager) is not None:
+                                message = msg_pkgmanager.format(
+                                    distname.title(), manager)
+                                break
             raise DistutilsSetupError(
                 "Cannot find cmake, ensure it is installed and in the path.\n"
                 + message + "\n"