Install script no longer works for updating installations since `_conda` became a symlink

### Solution to issue cannot be found in the documentation. - [x] I checked the documentation. ### Issue Starting from version 25.11.0-0, the file `_conda` inside the prefix directory is no longer a binary file, but a symlink to the `micromamba` binary. When running the install script with the `-u` flag for updating the current installation, the script fails as the symlink target already exists: ``` PREFIX=/root/miniforge3 Unpacking bootstrapper... ln: failed to create symbolic link '/root/miniforge3/_conda': File exists ``` ### Installed packages ```shell # packages in environment at /root/miniforge3: # # Name Version Build Channel _libgcc_mutex 0.1 conda_forge conda-forge _openmp_mutex 4.5 2_gnu conda-forge archspec 0.2.5 pyhd8ed1ab_0 conda-forge boltons 25.0.0 pyhd8ed1ab_0 conda-forge brotli-python 1.2.0 py312hdb49522_1 conda-forge bzip2 1.0.8 hda65f42_8 conda-forge c-ares 1.34.5 hb9d3cd8_0 conda-forge ca-certificates 2025.11.12 hbd8a1cb_0 conda-forge certifi 2025.11.12 pyhd8ed1ab_0 conda-forge cffi 2.0.0 py312h460c074_1 conda-forge charset-normalizer 3.4.4 pyhd8ed1ab_0 conda-forge colorama 0.4.6 pyhd8ed1ab_1 conda-forge conda 25.11.0 py312h7900ff3_0 conda-forge conda-libmamba-solver 25.11.0 pyhd8ed1ab_0 conda-forge conda-package-handling 2.4.0 pyh7900ff3_2 conda-forge conda-package-streaming 0.12.0 pyhd8ed1ab_0 conda-forge cpp-expected 1.3.1 h171cf75_0 conda-forge distro 1.9.0 pyhd8ed1ab_1 conda-forge fmt 12.0.0 h2b0788b_0 conda-forge frozendict 2.4.7 py312h4c3975b_0 conda-forge h2 4.3.0 pyhcf101f3_0 conda-forge hpack 4.1.0 pyhd8ed1ab_0 conda-forge hyperframe 6.1.0 pyhd8ed1ab_0 conda-forge idna 3.11 pyhd8ed1ab_0 conda-forge jsonpatch 1.33 pyhd8ed1ab_1 conda-forge jsonpointer 3.0.0 py312h7900ff3_2 conda-forge keyutils 1.6.3 hb9d3cd8_0 conda-forge krb5 1.21.3 h659f571_0 conda-forge ld_impl_linux-64 2.45 default_hbd61a6d_104 conda-forge libarchive 3.8.2 gpl_h7be2006_100 conda-forge libcurl 8.17.0 h4e3cde8_0 conda-forge libedit 3.1.20250104 pl5321h7949ede_0 conda-forge libev 4.33 hd590300_2 conda-forge libexpat 2.7.3 hecca717_0 conda-forge libffi 3.5.2 h9ec8514_0 conda-forge libgcc 15.2.0 he0feb66_15 conda-forge libgcc-ng 15.2.0 h69a702a_15 conda-forge libgomp 15.2.0 he0feb66_15 conda-forge libiconv 1.18 h3b78370_2 conda-forge liblzma 5.8.1 hb9d3cd8_2 conda-forge libmamba 2.4.0 hed7d790_1 conda-forge libmambapy 2.4.0 py312h17091a9_1 conda-forge libnghttp2 1.67.0 had1ee68_0 conda-forge libnsl 2.0.1 hb9d3cd8_1 conda-forge libsolv 0.7.35 h9463b59_0 conda-forge libsqlite 3.51.1 h0c1763c_0 conda-forge libssh2 1.11.1 hcf80075_0 conda-forge libstdcxx 15.2.0 h934c35e_15 conda-forge libstdcxx-ng 15.2.0 hdf11a46_15 conda-forge libuuid 2.41.2 h5347b49_1 conda-forge libxcrypt 4.4.36 hd590300_1 conda-forge libxml2 2.15.1 h031cc0b_0 conda-forge libxml2-16 2.15.1 hf2a90c1_0 conda-forge libzlib 1.3.1 hb9d3cd8_2 conda-forge lz4-c 1.10.0 h5888daf_1 conda-forge lzo 2.10 h280c20c_1002 conda-forge mamba 2.4.0 h7ae174a_1 conda-forge menuinst 2.4.1 py312h7900ff3_0 conda-forge msgpack-python 1.1.2 py312hd9148b4_1 conda-forge ncurses 6.5 h2d0b736_3 conda-forge nlohmann_json-abi 3.12.0 h0f90c79_1 conda-forge openssl 3.6.0 h26f9b46_0 conda-forge packaging 25.0 pyh29332c3_1 conda-forge pip 25.3 pyh8b19718_0 conda-forge platformdirs 4.5.0 pyhcf101f3_0 conda-forge pluggy 1.6.0 pyhf9edf01_1 conda-forge pybind11-abi 11 hc364b38_1 conda-forge pycosat 0.6.6 py312h4c3975b_3 conda-forge pycparser 2.22 pyh29332c3_1 conda-forge pysocks 1.7.1 pyha55dd90_7 conda-forge python 3.12.12 hd63d673_1_cpython conda-forge python_abi 3.12 8_cp312 conda-forge readline 8.2 h8c095d6_2 conda-forge reproc 14.2.5.post0 hb9d3cd8_0 conda-forge reproc-cpp 14.2.5.post0 h5888daf_0 conda-forge requests 2.32.5 pyhd8ed1ab_0 conda-forge ruamel.yaml 0.18.16 py312h4c3975b_0 conda-forge ruamel.yaml.clib 0.2.14 py312h4c3975b_0 conda-forge setuptools 80.9.0 pyhff2d567_0 conda-forge simdjson 4.2.2 hb700be7_0 conda-forge tk 8.6.13 noxft_ha0e22de_103 conda-forge tqdm 4.67.1 pyhd8ed1ab_1 conda-forge truststore 0.10.3 pyhe01879c_0 conda-forge tzdata 2025b h78e105d_0 conda-forge urllib3 2.5.0 pyhd8ed1ab_0 conda-forge wheel 0.45.1 pyhd8ed1ab_1 conda-forge yaml-cpp 0.8.0 h3f2d84a_0 conda-forge zstandard 0.25.0 py312h5253ce2_1 conda-forge zstd 1.5.7 hb78ec9c_6 conda-forge ``` ### Environment info ```shell active environment : None user config file : /root/.condarc populated config files : /root/miniforge3/.condarc conda version : 25.11.0 conda-build version : not installed python version : 3.12.12.final.0 solver : libmamba (default) virtual packages : __archspec=1=zen2 __conda=25.11.0=0 __cuda=0=0 __glibc=2.39=0 __linux=6.8.0=0 __unix=0=0 base environment : /root/miniforge3 (writable) conda av data dir : /root/miniforge3/etc/conda conda av metadata url : None channel URLs : https://conda.anaconda.org/conda-forge/linux-64 https://conda.anaconda.org/conda-forge/noarch package cache : /root/miniforge3/pkgs /root/.conda/pkgs envs directories : /root/miniforge3/envs /root/.conda/envs platform : linux-64 user-agent : conda/25.11.0 requests/2.32.5 CPython/3.12.12 Linux/6.8.0-90-generic ubuntu/24.04.3 glibc/2.39 solver/libmamba conda-libmamba-solver/25.11.0 libmambapy/2.4.0 UID:GID : 0:0 netrc file : None offline mode : False ```