The openblas package creates the following symlinks under /usr/lib:
$this->bbcode_second_pass_code('', '
libblas.so -> libopenblasp-r0.3.13.so
libblas.so.3 -> libopenblasp-r0.3.13.so
')
However, the destination file doesn't exist. Indeed, NumPy returns "Original error was: libblas.so.3: cannot open shared object file: No such file or directory".
If I delete these files and create
$this->bbcode_second_pass_code('', '
libblas.so -> libopenblas_armv7p-r0.3.13.so
libblas.so.3 -> libopenblas_armv7p-r0.3.13.so
')
the problem seems fixed