--- a/install	Sat Mar 07 09:31:06 2009 +0000
+++ b/install	Sat Mar 07 09:39:36 2009 +0000
@@ -1,17 +1,34 @@
 #!/usr/bin/env python
 
+import sys
 import shutil
 import os
 import pwd
 import subprocess
 
+# This must be run as root, because it must create an hg user.
+# Normally the clean thing to do is let it fail with a permission error
+# if a non-root user tries to run it, but I don't want anyone thinking
+# that they can make it work as non-root by changing install paths.
+# Patches welcome for doing this more cleanly of course.
+
+if os.getgid() != 0:
+    print >>sys.stderr, "Install must be run as root user"
+    sys.exit(-1)
+
+if len(sys.argv) > 2:
+    print >>sys.stderr, "Usage: install [<destination-prefix>]"
+    sys.exit(-1)
+if len(sys.argv) == 2:
+    dest = sys.argv[1] + '/lib/mercurial-server'
+else:
+    dest = '/usr/local/lib/mercurial-server'
+
 def installFiles(d, *sources):
     os.makedirs(d)
     for f in sources:
         shutil.copy(f, d)
 
-dest = '/usr/local/lib/mercurial-server'
-
 installFiles(dest,
     'src/hg-ssh',
     'src/refresh-auth')
@@ -47,6 +64,5 @@
     subprocess.check_call(
         "adduser --system --shell /bin/sh --group --disabled-password".split() + 
         ["--gecos", "Mercurial repositories", "hg"])
-        
     subprocess.check_call([dest + '/init/hginit'], preexec_fn = becomeFunc('hg'))