Mitigate lack of pyyaml on the running environment; Instruct to activate base before running this

conda/conda-bootstrap.py

@@ -24,10 +24,11 @@ environment.
 examples:
 
   1. Creates an environment called `myenv' for developing the currently
-     checked-out package:
+     checked-out package (N.B.: first activate the base environment):
 
      $ cd bob.package.foo
-     $ %(prog)s myenv
+     $ conda activate base
+     (base) $ %(prog)s myenv
 
      The above command assumes the directory `conda' exists on the current
      directory and that it contains a file called `meta.yaml' containing the
@@ -40,20 +41,23 @@ examples:
      the default python version to use for the newly created environment. You
      may select a different one with `--python=X.Y':
 
-     $ %(prog)s --python=3.6 myenv
+     $ conda activate base
+     (base) $ %(prog)s --python=3.6 myenv
 
   3. By default, we use bob.admin's condarc and `conda_build_config.yaml` files
      that are used in creating packages for our CI/CD system. If you wish to
      use your own, specify them on the command line:
 
-     $ %(prog)s --config=config.yaml --condarc=~/.condarc myenv
+     $ conda activate base
+     (base) $ %(prog)s --config=config.yaml --condarc=~/.condarc myenv
 
      Notice the condarc file **must** end in `condarc', or conda will complain.
 
   4. You may also specify the location of your conda installation, if it is not
      available on $PATH:
 
-     $ %(prog)s --conda=/path/to/conda myenv
+     $ conda activate base
+     (base) $ %(prog)s --conda=/path/to/conda myenv
 
 """
 
@@ -68,12 +72,6 @@ import tempfile
 import argparse
 import subprocess
 
-try:
-  import yaml
-except ImportError:
-  print('The package pyyaml must be installed alongside python')
-  sys.exit(1)
-
 
 def which(env, program):
 
@@ -95,6 +93,12 @@ def which(env, program):
 
 def get_rendered_recipe(args):
 
+  try:
+    import yaml
+  except ImportError:
+    print('The package pyyaml must be installed alongside python')
+    sys.exit(1)
+
   cmd = [
       args.conda, 'render',
       '--variant-config-files', args.config,