boot: Remove remote origin check

Previously, we used relative paths in submodules. When cloning from
GitHub, they had to be manually tweaked.
Since a76b233d we use absolute paths, so this workaround can be removed.

boot

@@ -28,43 +28,8 @@ def die(mesg):
     print_err(mesg)
     sys.exit(1)
 
-def check_for_url_rewrites():
-    if os.path.isdir('.git') and \
-       subprocess.check_output('git config remote.origin.url'.split()).find(b'github.com') != -1 and \
-       subprocess.call(['git', 'config', '--get-regexp', '^url.*github.com/.*/packages-.insteadOf']) != 0:
-        # If we cloned from github, make sure the url rewrites are set.
-        # Otherwise 'git submodule update --init' prints confusing errors.
-        die("""\
-            It seems you cloned this repository from GitHub. But your git config files
-            don't contain the url rewrites that are needed to make this work (GitHub
-            doesn't support '/' in repository names, so we use a different naming scheme
-            for the submodule repositories there).
-
-            Please run the following commands first:
-
-              git config --global url."git://github.com/ghc/packages-".insteadOf     git://github.com/ghc/packages/
-              git config --global url."http://github.com/ghc/packages-".insteadOf    http://github.com/ghc/packages/
-              git config --global url."https://github.com/ghc/packages-".insteadOf   https://github.com/ghc/packages/
-              git config --global url."ssh://git\@github.com/ghc/packages-".insteadOf ssh://git\@github.com/ghc/packages/
-              git config --global url."git\@github.com:/ghc/packages-".insteadOf      git\@github.com:/ghc/packages/
-
-            And then:
-
-              git submodule update --init
-              ./boot
-
-            Or start over, and clone the GHC repository from the haskell server:
-
-              git clone --recursive git@gitlab.haskell.org:ghc/ghc.git
-
-            For more information, see:
-              * https://gitlab.haskell.org/ghc/ghc/wikis/newcomers or
-              * https://gitlab.haskell.org/ghc/ghc/wikis/building/getting-the-sources#cloning-from-github
-        """)
-
 def check_boot_packages():
     # Check that we have all boot packages.
-    import re
     for l in open('packages', 'r'):
         if l.startswith('#'):
             continue
@@ -200,7 +165,6 @@ def check_build_mk():
                 https://gitlab.haskell.org/ghc/ghc/wikis/building/using#build-configuration
             """))
 
-check_for_url_rewrites()
 check_boot_packages()
 if not args.hadrian:
     boot_pkgs()