require git when trying to use it in ansible-galaxy cli (#49212)

* require git when trying to use it in ansible-galaxy cli

Previously we weren't setting `required=True` when calling
`get_bin_path` and the path would return `None`, this would cause
a traceback when attempting to ' '.join() to create a string
representation of the failed command for error output

Fixes #49200

Signed-off-by: Adam Miller <admiller@redhat.com>

* add changelog

Signed-off-by: Adam Miller <admiller@redhat.com>

changelogs/fragments/49212-require-git-ansible-galaxy.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+ - "ansible-galaxy: properly warn when git isn't found in an installed bin path instead of traceback"

lib/ansible/playbook/role/requirement.py

@@ -154,7 +154,7 @@ class RoleRequirement(RoleDefinition):
             raise AnsibleError("- scm %s is not currently supported" % scm)
 
         try:
-            scm_path = get_bin_path(scm)
+            scm_path = get_bin_path(scm, required=True)
         except (ValueError, OSError, IOError):
             raise AnsibleError("could not find/use %s, it is required to continue with installing %s" % (scm, src))