diff --git a/mercurial/hgweb/wsgicgi.py b/mercurial/hgweb/wsgicgi.py
--- a/mercurial/hgweb/wsgicgi.py
+++ b/mercurial/hgweb/wsgicgi.py
@@ -16,9 +16,7 @@ def launch(application):
     util.set_binary(sys.stdout)
 
     environ = dict(os.environ.items())
-    if 'PATH_INFO' not in environ:
-    	environ['PATH_INFO'] = ''
-
+    environ.setdefault('PATH_INFO', '')
     environ['wsgi.input'] = sys.stdin
     environ['wsgi.errors'] = sys.stderr
     environ['wsgi.version'] = (1, 0)
diff --git a/tests/test-hgweb b/tests/test-hgweb
--- a/tests/test-hgweb
+++ b/tests/test-hgweb
@@ -1,4 +1,5 @@
 #!/bin/sh
+# Some tests for hgweb. Tests static files, plain files and different 404's.
 
 hg init test
 cd test
diff --git a/tests/test-hgweb-no-request-uri b/tests/test-hgweb-no-request-uri
--- a/tests/test-hgweb-no-request-uri
+++ b/tests/test-hgweb-no-request-uri
@@ -1,4 +1,7 @@
 #!/bin/sh
+# This tests if hgweb and hgwebdir still work if the REQUEST_URI variable is
+# no longer passed with the request. Instead, SCRIPT_NAME and PATH_INFO
+# should be used from d74fc8dec2b4 onward to route the request.
 
 mkdir repo
 cd repo
diff --git a/tests/test-hgwebdir b/tests/test-hgwebdir
--- a/tests/test-hgwebdir
+++ b/tests/test-hgwebdir
@@ -1,4 +1,6 @@
 #!/bin/sh
+# Tests some basic hgwebdir functionality. Tests setting up paths and
+# collection, different forms of 404s and the subdirectory support.
 
 mkdir webdir
 cd webdir
diff --git a/tests/test-newcgi b/tests/test-newcgi
--- a/tests/test-newcgi
+++ b/tests/test-newcgi
@@ -1,4 +1,6 @@
 #!/bin/sh
+# This tests if CGI files from after d0db3462d568 but
+# before d74fc8dec2b4 still work.
 
 hg init test
 
diff --git a/tests/test-newercgi b/tests/test-newercgi
--- a/tests/test-newercgi
+++ b/tests/test-newercgi
@@ -1,4 +1,5 @@
 #!/bin/sh
+# This is a rudimentary test of the CGI files as of d74fc8dec2b4.
 
 hg init test
 
diff --git a/tests/test-non-interactive-wsgi b/tests/test-non-interactive-wsgi
--- a/tests/test-non-interactive-wsgi
+++ b/tests/test-non-interactive-wsgi
@@ -1,4 +1,6 @@
 #!/bin/sh
+# Tests if hgweb can run without touching sys.stdin, as is required
+# by the WSGI standard and strictly implemented by mod_wsgi.
 
 mkdir repo
 cd repo
diff --git a/tests/test-oldcgi b/tests/test-oldcgi
--- a/tests/test-oldcgi
+++ b/tests/test-oldcgi
@@ -1,4 +1,5 @@
 #!/bin/sh
+# This tests if CGI files from before d0db3462d568 still work.
 
 hg init test