install script's --prefix option isn't used by install_nbextension

[d-torrance]

Currently, python3 -m m2_kernel.install --prefix /foo will only install the kernel spec under /foo and not the nbextension.

I'm getting around this by using the following patch, but it would only work if it's known that notebook is installed under /usr.

--- a/m2_kernel/install.py
+++ b/m2_kernel/install.py
@@ -35,7 +35,8 @@
 
     print("Installing nbextension for syntax highlighting ...")
     install_nbextension('{}/m2-mode'.format(assets_dir),
-            nbextensions_dir='{}/static/components/codemirror/mode/'.format(notebook_dir[0]),
+            nbextensions_dir='{}/static/components/codemirror/mode/'.format(
+                notebook_dir[0].replace('/usr', prefix)),
             destination='macaulay2', overwrite=True, symlink=False)

[d-torrance]

To further complicate matters, if notebook is coming from the Debian/Ubuntu python3-notebook package, then the codemirror files are actually symlinks to the corresponding files from the libjs-codemirror package, and so we need to resolve those. Something like this:

--- a/m2_kernel/install.py
+++ b/m2_kernel/install.py
@@ -35,7 +35,9 @@
 
     print("Installing nbextension for syntax highlighting ...")
     install_nbextension('{}/m2-mode'.format(assets_dir),
-            nbextensions_dir='{}/static/components/codemirror/mode/'.format(notebook_dir[0]),
+            nbextensions_dir=os.path.realpath(
+                '{}/static/components/codemirror/mode/'.format(
+                    notebook_dir[0])).replace('/usr', prefix),
             destination='macaulay2', overwrite=True, symlink=False)