MANPATH needs a trailing ':' to utilize system defaults (#21682)

otherwise spack breaks using system man pages by default.

Co-authored-by: Harmen Stoppels <harmenstoppels@gmail.com>

lib/spack/spack/test/cmd/load.py

@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import os
+import re
 
 import pytest
 
@@ -16,6 +17,24 @@
 location = SpackCommand('location')
 
 
+def test_manpath_trailing_colon(install_mockery, mock_fetch, mock_archive,
+                                mock_packages, working_env):
+    """Test that the commands generated by load add the MANPATH prefix
+    inspections. Also test that Spack correctly preserves the default/existing
+    manpath search path via a trailing colon"""
+    install('mpileaks')
+
+    sh_out = load('--sh', '--only', 'package', 'mpileaks')
+    lines = sh_out.split('\n')
+    assert any(re.match(r'export MANPATH=.*:;', ln) for ln in lines)
+
+    os.environ['MANPATH'] = '/tmp/man:'
+
+    sh_out = load('--sh', '--only', 'package', 'mpileaks')
+    lines = sh_out.split('\n')
+    assert any(re.match(r'export MANPATH=.*:/tmp/man:;', ln) for ln in lines)
+
+
 def test_load(install_mockery, mock_fetch, mock_archive, mock_packages):
     """Test that the commands generated by load add the specified prefix
     inspections. Also test that Spack records loaded specs by hash in the

lib/spack/spack/util/environment.py

@@ -611,7 +611,6 @@ def apply_modifications(self, env=None):
     def shell_modifications(self, shell='sh', explicit=False, env=None):
         """Return shell code to apply the modifications and clears the list."""
         modifications = self.group_by_name()
-        new_env = os.environ.copy()
 
         if env is None:
             env = os.environ
@@ -622,6 +621,9 @@ def shell_modifications(self, shell='sh', explicit=False, env=None):
             for x in actions:
                 x.execute(new_env)
 
+        if 'MANPATH' in new_env and not new_env.get('MANPATH').endswith(':'):
+            new_env['MANPATH'] += ':'
+
         cmds = ''
 
         for name in sorted(set(modifications)):

var/spack/repos/builtin.mock/packages/mpileaks/package.py

@@ -28,6 +28,7 @@ class Mpileaks(Package):
 
     def install(self, spec, prefix):
         touch(prefix.mpileaks)
+        mkdirp(prefix.man)
 
     def setup_environment(self, senv, renv):
         renv.set('FOOBAR', self.name)